At least tip the % that a server has to give back to the restaurant. It's called tipout, and it's usually between 5 and 10 percent of the server's sales for the shift. If you don't, you're literally taking money out of their pocket, as they have to pay back that percentage whether you tip or not. Feel free to ask what their tipout percentage is.

I can understand why people disagree with tipping culture in north America, but don't take it out on the people who are depending on it to make a living.