Originally Posted by
Peterpan1
"Then why isn't it included in the price? "
In some restaurants it is automatically added to the bill, though it is rare where I live.
The reason is that the service provider has a split loyalty. Everything from how time is alloted to various people and tasks, to whether they promote specials that are in the establishment's interest but perhaps not yours. Tips even that out, so that you are paying for the service directly and can influence the server so that you get good service.
So, you have to pay a bribe to get good service!
You know, the more I think about the tipping system in the United States, the less sense it makes to me. Thanks to the OP for bringing this up.