The self check out machines have improved over the years, mostly (stupid fcking Jewel). I hated the experience of:
"return the item to the bagging area"
"You removed an item from the bagging area"
"an unknown item is in the bagging area"
Produce is also annoying to do self checkout.
Thats when you leave a full cart of groceries at the self check out and walk out in a minor rage