The example you gave is sad but true.
The worst part of all is that the girl at the counter didn’t just total up the purchase and then enter in the exact amount of money you gave her. The register then would have told her that .50 cents was gonna be your change.
Besides being unable to think for herself, she wasn’t even willing (or able) to let the cash register do the thinking for her.
This is not a new phenomenon. Back in the 70s, before cash registers did the thinking, my parents hired a waitress who was a math major at the local community college. A customer bought an item that totalled 26 cents (this was the 70s, after all) and gave her $1.01. I had to tell her how to make change for that. I was about 14 at the time. Needless to say, I didn’t even consider that college when I was looking for a school!!