As of now, my local supermarkets still have price tags on the shelves. And if there's a higher price at the register when the item is scanned, they will honor the shelf price if you call it to their attention. The biggest supermarket now has e-ink shelf tags so I assume those are synced with their item database so that doesn't happen anymore.
it's the other way around, the shelf prices can be stable and they decide which discounts you can get based on your shopping profile which they built using surveillance