Some restaurants do add on an additional tip,and make you pay it. I went out to eat with 10 friends, then bill came at the end with a mandatory tip. 1) the waiter basicalyl took our order and passed out the food, it was the bus person that did most of the work. 2) the waiter was rude to almost everyone at the table. 3) when we tried to pay the bill minus the tip (because of the service) the owner almost called the cops on us!

There are enough people that dont tip enough on their bills for adequite service. Yes, some servers may be missing out on a tip, but if everyone tips 15 percent, it makes more money than if one person tips 20%, and all the others til 10%