The price tag may become personal before you reach the shelf

A retail concept now discussed among grocery chains would connect electronic shelf labels to the shop's loyalty app, so that the price a customer sees is produced for that customer. Walk into the aisle with the app open, and the label would resolve to a figure calculated from the basket, the visit history, the hour and whatever else the model has been permitted to weigh. Walk in without the app and the label would show a price too. Just not the same one.

The chain's position would be that nothing has become more expensive. Every personal price would be presented as a discount: applied automatically, needing no coupon and no request. The difficulty would be arithmetic rather than moral. A discount is a number subtracted from another number, and the other number would no longer exist in any form the shopper could inspect.

Two customers comparing labels in the same aisle would discover that they are not comparing anything. Price comparison assumes the price is a property of the product. A price that is a property of the person turns the weekly shop into a series of private negotiations conducted by one side only, at a speed the other side cannot follow, over an amount neither party could justify afterwards.

“This is not surveillance pricing,” a spokesperson for a chain running a pilot would say. “It is relevance. The customer receives an offer suited to them.” Asked whether a customer could see the offer suited to somebody else, the spokesperson would say that this would not be relevant.

Regulators would find the existing rules almost, but not quite, adequate. European price-indication law requires a shop announcing a reduction to state the lowest price it charged in the preceding thirty days, precisely so that reduced means something. A system in which every shopper has their own preceding thirty days would satisfy the letter of the rule while removing the thing the rule was written to protect.

The receipt would become the last honest document in the shop, and would be quietly redesigned. Shoppers who photograph and compare their receipts would report that the totals always match what they saw on the shelf, and never match each other. That is the most unsettling possible outcome: nothing is wrong, and nothing can be checked.

No chain has proposed this publicly. The hardware is going up in the aisles for other reasons, the apps already tailor coupons, and other industries are beginning to price individually and to call it optimisation. What is being described here is not a new capability. It is the decision to let the label, rather than the coupon, be the part that knows who you are.