It is not legal to charge a different price at the register. Also, it would be quite difficult to ensure the price you pay at the register matches the price you saw on the shelf ten minutes ago.
If you suspect they are changing prices on you from the time you leave the shelf, take a photo of the price. If it's different at the register, you know it was changed.
It's not that granular. They're going to use surge pricing, so when you shop is going to matter a lot. The tag will match the till. Going to buy beer and hot dogs on game day? Surge pricing!
Why? I can match the till and tag automatically and slip in a 30 minute grace period between. The number of customers who would be impacted would likely be marginal.
It definitely takes me longer than 30 mins to get through the store.
But the "why" is that I think a single customer being overcharged by this system is too many. I know it happens a lot by accident at the moment because staff screw up the paper price tags, but having it by design is no longer an honest mistake.
And worse, the answer to this problem is probably going to be "facial recognition" and I hate that even more.
It would be really hard to guarantee it. There are definitely times it has taken more than an hour to go around the store. It takes at least 45 mins on a normal trip, and the more kids that are with me the longer it takes. You need a lot of groceries when you're eating for 5.