Where I get my groceries there is never a wait to check out longer than a minute, and usually none at all. The checkout girl rings up my groceries as fast as I put them on the belt. Meanwhile the bagging girl or guy is loading the bags with groceries and putting them on a cart. She's usually wrapping that up just about the time I'm scanning my credit card. Then she carts my groceries out to my SUV and loads them in the SUV.
Explain how self-checkout could possibly improve on that experience.