Here a store has to display prices for a high percentage of the items on the shelves and if there is a discrepancy at the register the displayed price is the decider.
It'd also be perfectly possible to implement different prices with a traditional barcode scanner. Just have a button on the register (or say, give a discount if the person signs up for a store card...).
If the customer notices a discrepancy, they give them the lower price. They win out in the long run since it depends on the customer to notice the discrepancy and point it out.
Any minor advantage at their scale wins out as a pretty big deal.
What you described is called fraud.
That kind of fraud is what the corner bodega does, not what Amazon does.
I think a better approach would be to display an initially high price, and mention automatically applied coupons at checkout - or require the user to use their smartphone's app to apply the coupon.
Maybe it depends on the state, and its laws on price marking.
$3.75 each Or buy two and get the second one at 25% off with bonus card.
I suspect that few customers do the mental arithmetic to figure out what their final cost will be.
https://www.recode.net/2018/1/21/16913984/what-does-photos-a...