We hate waiting in line at the cashier and stores don't like paying cashiers so some have self-service cashiers which are still hard to use. So here's an idea.
Provide shoppers who wish to self-serve a scanning wand, which is battery powered and attached by coiled cable to the shopping cart. In the shopping cart, have a number of shopping bags present and numbered. Paper bags which hold a square shape are better. Also have an open area or special bag.