When visiting US I feel very weird about baggers. Bagging stuff is something I can easily do myself while the cashier scans the products. Now instead of doing something useful, I just stand there idle and awkward watching the staff working.

In general having service workers spend a good part of their lives doing things that I can trivially with minimal effort and no loss of time do myself feels actively degrading these people. Perhaps some do get sense of being useful out of it, but I'd guess a lot of them would rather be doing something else if given choice.