Walmart already has something of the sort. A few days ago I was self-checking my groceries. I had rung up a carton of milk and put it back into the cart, then decided a minute later to include the milk in a bag of other refrigerated stuff. When I moved the milk to the bag, it set off some sort of alarm that I had moved an item from the cart to the bagging area without scanning it. The attendant came over and I scrolled back up the checkout screen to show that I had already scanned the milk, and that was that.
Walmart already has something of the sort.
CO, Same at City Market, every time i self checked at a busy store, i got flagged for Help is on the Way when i pushed the final No Bags Needed button. Turns out the monitor system was recognizing my brown leather cased phone i the shopping cart as an unscanned item. When one of the regular checkout watchers, Stacy, finally told me to put your phone in your pocket before checking out, my ‘ problem’ went away.