custom. And people accept these jobs because of that custom, which in America, is to tip (usually) between 15-20 percent.
So when someone plans to dishonor the custom that the other side is relying on in agreeing to provide service, I think it's moral to say that up front. That's my point here. Simply because you are able to do something, like not tip as you should after good service, doesn't make it right. Obviously you hold all of the cards when you're the one doing the tipping, so no one can force you to do anything. I guess what you do with those cards is just a matter of character.