I like the ones that aren't user-hostile. For example IKEA near us has these. You just quickly scan everything and pay. The only slight annoyance is one "Are you sure you scanned everything, you are on camera" nag. I can get through quickly and bag everything as I like.

However most stores by me have mandatory delays after every item as it weighs your bagged of scanned items to make sure you didn't slip something you didn't scan in there. It painfully slows down the process even the times where it doesn't misfire.

On the contrary, I use self checkouts at much as possible. I'd rather wait in line for one than deal with a person

Many software engineers I know just don’t like interacting with people. Machines are better unless they are buggy UIs.