Your plan fails in a few ways.

Refreshing the content on an electronic shelf label (ESL) takes about 30 seconds, and multiple people can view a product simultaneously. Unless the store is giving everyone AR glasses, people will notice the price discrepancy.

This assumes you have sufficient data to actually recognize a shopper such as facial ID or some form of iBeacon for every single product for which you wish to implement price discrimination. Basic ESLs cost $3 to $12, depending on size and use very little energy. Adding a camera means more energy, so a bigger battery and more cost.

Using in-app discounts is the most likely way to implement this, which I am okay with. Shoppers are willingly trading their data privacy for a discount.

I think viewing it at as a discount is framing it wrong. It’s more a fee for not using the app, and if you use the app you’ll get charged the highest price McDonald’s has decided you will pay.

Should this be legal is a question you could argue both ways, but in my opinion society will be worse off with per customer pricing.

> Using in-app discounts is the most likely way to implement this, which I am okay with. Shoppers are willingly trading their data privacy for a discount.

I'm not OK with this. Simple reason, it leaves the wide masses with no other option than to sell their data to survive.