見えないマークアップ：InstacartがChatGPTに参入するにつれて、誰が価格を設定するのか？

The dream of “conversational commerce” has been the holy grail of Silicon Valley for a decade. Alexa tried to do it with voice. Meta tried to do it with chatbots in Messenger. But today, Instacart may have just crossed the finish line—and started a new race entirely involving your wallet.

This morning, Instacart became the first grocery platform to launch a fully integrated “Instant Checkout” experience directly inside OpenAI’s ChatGPT. It’s no longer just a recipe suggestion; it is a direct pipeline from an LLM prompt to a finalized transaction.

However, as conveniences multiply, so do the shadows. As we hand over the keys to our shopping carts to algorithms, a darker pattern is emerging from recent investigations: the rise of the “Invisible Markup.”

The “One-Click Dinner” Promise

For the uninitiated, the new integration is technically impressive. Previously, using the Instacart plugin required a clunky handoff: ChatGPT would generate a list, and you would click a link to be taken to the Instacart app to review and pay.

The new implementation uses OpenAI’s latest “Actions” API to handle the cart-building and checkout flow natively. You tell ChatGPT, “I want to make a spicy vodka pasta for four people tonight, but I’m gluten-free.”

In milliseconds, the AI:

1. Parses the Intent: Identifies the dish and the dietary restriction.
2. Selects Products: Chooses specific SKUs (e.g., Tito’s Vodka, De Cecco Gluten-Free Penne, Organic Heavy Cream).
3. Builds the Cart: Adds them to your linked Instacart basket.
4. Executes: Presents a “Pay Now” button directly in the chat interface.

It is frictionless. It is magical. And it relies entirely on you not checking the price of the pasta.

The Technical Deep Dive: Structured Data vs. The “Black Box”

To understand the risk, you have to understand how the sausage—or the vegan sausage alternative—is made.

When you shop manually, you are performing a constant, subconscious audit. You see the gluten-free pasta is $4.99. You scan the shelf (or the scroll view) and see the store brand is $3.49. You make a choice.

In an LLM-driven commerce flow, this “Audit Layer” is removed. The AI selects the SKU based on a complex weighing of:

• Relevance (Does it match the prompt?)
• Availability (Is it in stock?)
• “Commercial Weighting” (This is the black box).

“Commercial Weighting” is the industry euphemism for sponsored placement and margin optimization. Instacart has built a massive ad business (now accounting for nearly 30% of their revenue profit pool) by auctioning off shelf space.

In a search results page, “Sponsored” items are marked. In a chat response, where the AI simply says, “Here is your cart,” that transparency evaporates. The AI isn’t just a shopper; it’s a salesperson who works on commission.

The “Invisible Markup” Controversy

This launch comes at a particularly awkward moment for the grocery giant. Just this week, a stinging report from Consumer Reports (highlighted by investigations in Arizona and Florida) accused Instacart of running “AI-enabled pricing experiments” that resulted in identical users seeing vastly different prices for the same goods.

The Mechanics of Personalized Inflation

According to the analysis, the pricing discrepancies weren’t just random glitches. They followed a pattern common in algorithmic pricing models used by airlines and ride-share apps, but new to groceries:

1. Demand Surging: Users in “high-demand zip codes” saw markups of 5-7% on staple goods compared to users just a few miles away.
2. History Profiling: Users who historically accepted high-markup items without removing them were shown “premium” brand options by default more often than price-sensitive users.
3. Obfuscated Fees: In some test cases, the service fee was lowered while item prices were raised, maintaining the total cost but hiding the markup in the SKU price—a practice known as “shrouding.”

When you combine Shrouding with ChatGPT Automation, you create a perfect storm for consumer exploitation. If the AI selects the $8.99 organic strawberries instead of the $4.99 conventional ones, and you are just clicking “Pay” on a $150 cart, the markup is effectively invisible.

$\text{Total Markup} = \sum (\text{Algorithmic SKU Premium}) + \text{Dynamic Service Fee}$

In the manual world, you catch these. In the automated world, you don’t.

Contextual History: The Costco Precedent

This isn’t Instacart’s first brush with pricing controversy. The platform has long had a tenuous relationship with price transparency, most notably with Costco.

For years, Costco members have complained that Instacart prices are significantly higher than in-store prices—often by 15-20%. Instacart discloses this with a “Higher than in-store prices” disclaimer, but the math is often opaque.

In 2024, a class-action lawsuit (still pending certification) argued that the “markups” were being applied deceptively, with users believing they were paying for delivery fees when they were actually paying per-item premiums.

The shift to AI exacerbates this. If an AI “Agent” is acting on your behalf, does it have a fiduciary duty to you (the user) to find the lowest price? Or does it have a duty to Instacart (the platform) to maximize cart value?

Currently, the legal answer is the latter. The ethical answer is the former. The gap between the two is where your money is disappearing.

Forward-Looking Analysis: The “Agentic” Regulation Era

The launch of Instacart on ChatGPT is likely the “Netscape Moment” for AI Commerce. It proves it works. But it will also likely be the catalyst for the “GDPR of AI Commerce.”

We predict three major regulatory shifts in the next 18 months:

1. Mandatory SKU Comparison: Regulators in the EU (and likely the FTC under its current aggressive stance) will demand that AI agents present a “Price Comparison” options—showing the selected item alongside the cheapest alternative.
2. “Fiduciary AI” Standards: A legal designation that if an AI claims to be a “Personal assistant,” it must prioritize user savings over platform revenue unless explicitly told otherwise.
3. Audit Logs for Receipts: A requirement for platforms to show exactly why a specific product was chosen (e.g., “Selected Brand X because it was sponsored” vs. “Selected Brand X because it was the only one in stock”).

The Verdict

For now, the advice for the tech-savvy shopper is simple: Trust but Verify.

Use the ChatGPT integration. It is genuinely a time-saver. Let it plan the meal. Let it find the gluten-free pasta. But before you click that glowing “Checkout” button, force the system to show you the itemized list.

In the age of AI, convenience is cheap, but control is expensive. Don’t pay the invisible tax just to save five minutes.