They're working hard for you. But there are times when they all cross the line. I ate dinner in a coffee shop one night. All I had was two twenties. The waiter picked it up, looked at them, saw the total on the bill, and asked if I needed change.
Cocktail waitresses are another good example.
They'll gladly pay you. Then they'll stand there, looking at you. I've actually heard some of them talking to each other. Not about me, thankfully. But about another player who hit a royal on a quarter machine.