> Scan as you shop is a big step backwards and feels like you've got the annoying self-checkout experience looming over you the entire time you're there.

How do the Amazon "Dash Carts" actually work though? If it were a traditional bar code scanner, I'd agree with you. But reading up on the tech makes it sound like you just place the item in your cart and that's it. If it worked like that I don't see at all what the problem would be.