The chain "Meijer" has this option. It slows down the process while you're actually finding the items in the store, but drastically speeds up the checkout process as the cashier only has to "verify" between 3-7 items. They just randomly grab them from whatever is on top of the cart, scan them, and away you go!
Walmart now has this. The first time I used it I was asked to allow a random screening of 3-7 items, but since then I have not had to deal with that. Just scan and go.
In Switzerland the two major grocery stores have this system. You need to establish trust first, for the first few months you'll get more inspections. But I haven't been checked in years now.
I use the mobile phone checkout for one of the stores I go to. Every time when leaving, they manually inspect every single item in my cart.