A16z: Five "No-Go Zones" for AI Payments and Opportunities for Stablecoins

Author: SamBroner, a16z Crypto

Translation: Block Unicorn

Preface

Walking through a marketplace as a tourist, you see a lively scene: people bustling around, eyes fixed on goods, comparing items, tasting, bargaining with vendors, exchanging currency. It appears to be a one-time transaction—each interaction a small negotiation, trust maintained through cash, or value exchanged via bank cards.

But this isn’t how most transactions on the marketplace operate. Look closer: most people are locals heading purposefully to their favorite merchants. Restaurant owners visit friends, butchers, fishmongers, and farmers. Tailors go to repair shops, weavers, and artisans. They all operate on credit.

When we discuss how smart agents will handle payments, we tend to unconsciously think from a tourist’s perspective.

But smart agents will behave more like locals. The difference between smart agents and humans lies in their characteristics—unlimited copying, flexible resource allocation, zero startup costs—which means a few smart agents can dominate niche markets. Even as creating smart agents becomes easier, human relationships, partnerships, and trust still help craft successful user experiences. Dominant smart agents won’t need tourist payment channels; they need vendor relationships, working capital, and credit. Smart agents can guide tourists (that’s you) forward.

What does this specifically mean? As smart agents integrate into business platforms, their payment methods must shift from retail channels to pre-negotiated B2B terms and credit, which current payment channels can’t fully support. If entrepreneurs develop excellent solutions for next-generation payment scenarios—like smart agents, streaming payments, and high-frequency, low-value transactions for global businesses—then next-gen payment channels (e.g., stablecoins) will have growth opportunities.

This article explores this idea from three angles: how the differences between smart agents and humans influence which payment strategies succeed; the shortcomings of current methods; and what elements the next-generation payment channels need to succeed.

Differences Between Smart Agents and Humans

To understand the relationship between smart agents and payments, we must consider two questions: Will smart agents behave more like humans or like enterprises? Will they focus on long-term or short-term interests?

Smart agents will behave more like enterprises, establishing long-term relationships with vendors and partners. They are lightweight, customized individuals built on large corporate architectures—like a perfect tour guide from a well-connected travel agency, or franchisees that can adapt services to local tastes without renegotiating supply chains.

Why will smart agents act like enterprises?

First, optimal experiences stem from careful design. I don’t want an agent that’s still negotiating, comparing prices, and bargaining at checkout. I want an agent that has already done that—knows which vendors are reliable, has pre-negotiated prices, and can settle immediately. That’s business relationships, not travel transactions.

In fact, human agents have long existed: travel agents are one example, but literary agents, talent agents, watch dealers, real estate brokers—many others—also build key multi-party relationships with publishers, production companies, watch distributors, or mortgage lenders, with each transaction tailored on that basis.

Second, while smart agents can be infinitely replicated, scalable business models (and their advantages) cannot. Excellent smart agents leverage economies of scale: lower computing costs, better vendor pricing, deeper integrations, and more deterministic components. Scale breeds scale. An agency booking a million flights a year can negotiate better terms with airlines than one booking only ten.

We see this trend already. Only ChatGPT has enough channels to negotiate partnerships with Shopify, Amazon, Expedia, and others. Small startups can only use automated browsers or reverse-engineered APIs, paying high retail fees.

That’s why smart agents will consolidate or at least be built on larger platforms. While easy to develop, the economic benefits mean each vertical’s agent count should be limited—deep vendor relationships and enough profit margin to reinvest in user experience. Vertically integrated, vendor-strong agents can work in tandem with user agents, creating a win-win.

Two Payment Relationships

If smart agents operate more like enterprises, then two payment relationships must be designed: user → agent, and agent/platform/guide → vendor.

Users pay the agent—via subscription, task-based fees, credit lines, or authorized account access. The agent pays vendors through negotiated B2B terms, bulk pricing, 30-day invoices, or via sub-agents. Currently, the agent occasionally pays vendors through retail channels, but this only accounts for a small part of total expenditure.

This mirrors how credit cards work today: issuing banks establish retail relationships with consumers, take on risk, offer rewards, and provide credit limits. Acquirers build business relationships with merchants, negotiate terms, handle bulk transfers, and manage complex working capital.

Smart Agents and Credit Cards: A McKinsey-Style Perfect Match

As many have noted, credit cards are actually a pretty reasonable payment product for smart agents. They are widely accepted; payments between $20 and $1,000 are considered reasonable; and they come with built-in arbitration, cancellations, and digital features.

Credit cards also provide monthly statements—an important way for consumers to understand their spending—and as smart agents replace kids playing on iPads as sources of accidental spending, this concept will only improve.

But there are two issues: first, credit cards are technically a poor fit for smart agents. Second, their fee models trap the industry in a classic innovator’s dilemma.

Credit Card Technology Is Difficult to Upgrade

Almost all credit card tech relies on human intervention: approval processes, user interfaces, and traditional payment methods (single payments, subscriptions). Products like Stripe Link, Visa 3D Secure, and dozens of virtual card solutions—allowing you to save cards on websites or register cards for recurring monthly subscriptions—have only matured over 15 years.

The adoption speed of smart agents is so rapid that thousands of PSPs, POS terminals, merchants, and client devices cannot upgrade their interfaces, programmability, or fraud detection fast enough to support this new payment flow.

Credit Cards Fail for High- and Low-Value Transactions

Imagine a smart agent paying a compute provider or small API access fee. Neither can be paid via traditional credit card channels. Visa, for example, doesn’t support payments below one cent; its fee model expects a flat 30 cents per transaction. While Visa could develop streaming or micro-payment tech, convincing stakeholders to accept lower revenue is harder.

More troubling, credit cards are caught in the innovator’s dilemma. Despite similar user relationships and needs, smart agent payments often involve amounts outside the $20–$1,000 range. Many initial solutions involve paying for APIs that are hard to refund or resell (fraud risk). Credit cards aren’t impossible, but the long-standing dilemma weakens existing players.

Even without credit cards, traditional payment channels will still have a role in the future.

Existing Payment Methods Will Still Play a Role

As smart agents become integrated into platforms resembling business entities, most large-value expenditures will shift to pre-negotiated B2B terms: invoices, 30-day net payments, discounts, and credit lines. In that world, “payment channels” can be anything—often asynchronous settlement over traditional channels. Fees are shared across larger transactions, and working capital is negotiated.

But the scope for smart agents isn’t limited to this. They are already operating in areas where traditional payments struggle: first-time onboarding, cross-border payments, streamlining complex reconciliation, new agent-vendor models, instant payments to reduce borrowing costs, and microloans.

In these scenarios, stablecoins are a better payment option, and building the next generation of features on programmable money is much easier than on traditional infrastructure. New partnerships built on stablecoins will evolve into ongoing relationships. As stablecoin payment platforms go live, they—being cheaper, faster, and more global—are likely to occupy an increasingly important share of the payment mix.

Opportunities in New Payment Technologies

To understand future trends, we should focus on technologies best suited for growing application scenarios.

Stablecoins—faster, cheaper, globally accepted currencies backed 1:1 by high-quality liquid assets—are a new platform capable of meeting unmet needs in areas like international payments and streaming payments. Crucially, stablecoins are programmable. Arbitration, monthly (or hourly) settlement, credit, escrow, and conditional payments can be flexibly extended to support many new use cases. Unlike bank or credit card payments, stablecoin payments can be easily integrated into APIs, databases, and agent checkout systems, significantly simplifying reconciliation, approval, and onboarding—crucial for entrepreneurs building agent businesses.

Practically, stablecoins solve the unit economics issues of credit cards in extreme cases. They have no $0.30 minimum fee, avoiding small-value payment problems. They don’t erode profit margins on large transfers with interchange fees. Smart agents pay compute providers $0.001 per second, while vendors settle $50,000 invoices—both using the same payment channel. This flexibility is vital for engineers and entrepreneurs designing their next platform.

Building More Stablecoin Infrastructure

The most common objection to stablecoins is the high cost of deposits and withdrawals. For tourists unfamiliar with stablecoins, this is true—unless they are accompanied by a guide or smart agent. Guides can help tourists exchange currency and facilitate necessary transactions precisely, saving on fees.

Adding billing and arbitration features to our stablecoin-enabled guide services brings us closer to an ideal system.

Imagine shopping in a department store. You browse multiple vendors, add items, and finally settle a consolidated bill. The platform handles the complex process of distributing funds to each vendor. Smart agents need a similar model: a unified view showing purchase intents across multiple vendors, with one-click approval of bulk orders. Users see “Your smart agent wants to book flights, hotels, and car rentals,” rather than three separate checkouts. The agent platform manages vendor relationships, while users manage purchase intents. Users can approve, review, or dispute transactions.

While credit cards handle arbitration well, new payment channels need to extend this. When margins are high or returns are easy, arbitration is straightforward—like flights within a 24-hour cancellation window, pre-activated subscriptions, or luxury goods with high margins that can afford refunds. Early agent use cases often involve low-margin digital goods—compute resources, API calls, or food delivery.

Summary

Smart agents won’t pay like tourists. They will pay like locals—through relationships, credit lines, and repeat business. This means real payment flows will be based on pre-negotiated B2B terms, not card swipes. Frankly, pre-negotiated B2B terms don’t require new payment channels. Settlement layers can be anything—wire transfers, ACH, or batch transfers. Traditional payment methods are perfectly sufficient for established relationships.

But we are at a pivotal moment. Smart agents are emerging, entrepreneurs are building their systems, and they need payment methods that work immediately—not ones that require years of credit card tech upgrades. Credit cards aren’t ready: they’re too costly for small payments, hard to reconcile, burdened by technical debt, and human factors influence fraud decisions. Stablecoins are mature. They are programmable, global, easy to reconcile with digital services, and can be integrated into APIs and agent checkout flows from day one—even without negotiated merchant agreements or complex B2B setups.

This is a critical moment. Entrepreneurs building smart agents today will choose tools that can operate effectively right away. Payments are sticky. Ultimately, new relationships built on stablecoins will evolve into old relationships still based on stablecoins. Over the next few years, the ecosystem will mature, barriers to entry will lower, and infrastructure gaps—like billing, arbitration, credit, batch approval, and interoperability—will be filled by startups built on stronger foundations.