If I’m reading this right, it assumes that each shopper is shopping by themselves, and therefore has one app-enabled phone per shopper to track purchases with.
What happens if a family is shopping? Or a group of friends with only one phone to open the door with? If someone enters by following another person through the door instead of using their own smartphone, can they leave without being tracked?
Could be confusing. “Oh, Junior, you need to scan that before putting it in the cart, or we will get stopped at the door to correct it.” I think the point is to associate the item with the paying account, and then to commit the sale by leaving the store with it.