Walmart and Sam's Club have exactly that with their Pay & Go app. You scan the UPCs on things as you put them in your cart. When you're done, you select pay an

Walmart and Sam's Club have exactly that with their Pay & Go app. You scan the UPCs on things as you put them in your cart. When you're done, you select pay and it displays a barcode on your screen. The checker at the door has a handheld device that they scan the barcode with, it gives them an item count, and you're on your way. I've only ever used it at Sam's where there's always a door checker. I've heard it can be more of a pain to use at Walmarts because the door people don't always have the handheld around and have to go hunt it down. Really, it shouldn't be surprising that they'd be a company willing to experiment in this field. Cutting labor costs to an extreme (which is actually one of the reasons I avoid Walmarts, but that's another rant) is pretty central to how they operate. And they became the behemoth they are by innovating in logistics. People often forget that they were a key figure in driving the adoption of product barcodes in the first place.