That is something that was never prolific where I live. There is a single 7-11 that I know of within 30 miles of me. I have only ever been there once and that was 20 years ago. I know it is still open, but never had a reason to go there vs anywhere other place.
Depends on the location. The Walmart near me has 16 smaller stations and 8 "normal sized" stations. All are normally running vs maybe 5 of the 20 manned registers during normal business hours, 1 or maybe 2 manned lanes after midnight. So those lines normally go much faster given that you are able to get to a self check out faster than a manned station. Addition of self checkout did not change the number of manned stations, just allowed more lanes to check out really. Normally I can get to a self checkout lane by just walking up to one while manned lanes might have 4 - 6 people waiting in a line.
I view my time as having value. If the self checkout line gets me out of the store 5 - 10 minutes faster that is of value to me. If your time has no value then yes your statement is true.
My walmert is run like shit. I go for self checkout if there are a lot of people waiting in line. But my Walmart has about 8 self checkout lanes. But the problem is the idiots that run it have like 2 cashiers running. Its like shit. Plus the self checkout computers are really laggy and slow. I am not sure what they did here, the Walmart is actually a super center and fairly new. On the other hand Target right across it has a good balance and only 4 self checkout counters but their computers are super fast and no lag at all. When I only have like 2 items I am grabbing I go for self checkout. if I have a lot of items I don't bother scanning them all.
Walmart self checkouts for me get clogged because they have like 2 cashiers open so almost everyone goes to self checkouts so it sort of defeats the purpose. lol