> So how the heck would a grocery store even do this? And this law is specifically around grocery stores.

Can't you just (in principle) use facial recognition cameras to determine who is approaching an item, calculate a "personalized" price and display it before they pick up the item, then make sure you match it at checkout? You could even use computer vision to only update price labels when people aren't looking at them, predict walking trajectories to pre-load prices and pre-resolve conflicts, and in ambiguous/low-confidence situations you could fall back on a default price.

This all sounds a bit like science fiction, but there is some prior art with Amazon's retail experiments, and it seems like this sort of thing is getting easier and cheaper all the time.

edit: some people have noted that you can have prices only visible viable via scanning qr codes, which makes this all much simpler. But I think you could do it with visible price labels too---you would lose some opportunities to jack up prices e.g. when multiple people are in close proximity to an item, but you could still profit in the (likely a majority of) situations where that's not the case.