We live in a dust material world, most of time we have to do something according to the rules that formed generation after generation.
We have to get something to support our families. Most of time we have to please others for our own benefits
The managers ask their employees to smile when wait the guests. I'm sure it's a way to please their guests for their benefits.
It's not a dirty thing to please others. It's a win_win result to make others feel pleasure at the same time to get something we want.