Tipping is something completely different. I have come to believe that in America tipping is to recognize acceptable service. It is a feedback mechanism to weed out, to mark and penalize undesirable behaviors. The best people to make that determination are the customers themselves.

The only time you should not tip is when the service is bad.

Do understand that if we did not tip the prices would simply rise, we would still pay the same as with tipping, but it would take away a mechanism by which you can make ourselves heard.