The price being what's marked on the shelf tag isn't the problem; the problem is going to the supermarket at, say, 0600 on a Tuesday morning and the 28-ounce container of Maxwell House coffee is $14.99, but if you shop at 1100 on a Saturday, the same product is tagged $16.99, because there are more shoppers and more demand. Or, in a more excessive case of fearmongering ridiculous scenarios, using AI hooked to the cameras that are all through stores to track shoppers, judge their financial status based on their appearance, and scale prices accordingly -- not only would this require a great deal more discrimination on the part of the AI system than they seem to be capable of now, but has the additional overhead of tracking the tagged price for the customer that took the product off the shelf and link it to the register -- and it doesn't account for trivial counters like person A doing the shopping, then turning the cart over to person B for the checkout.