Servers like it because they can abuse information asymmetry to get more money. If I sit down at a restaurant, I don't know if the server has had a good week,

Servers like it because they can abuse information asymmetry to get more money. If I sit down at a restaurant, I don't know if the server has had a good week, a bad week, an average week, or what. So, not knowing that, if I'm sympathetic to their position, I'm inclined to tip well. Add on to that the constant pressure of tips upward. It's gone from being 10% on average to 20% on average in my lifetime. And also flat rates on certain services.