It is terrible, but it's the system we have here in the US. I'd like to see it changed, but in practice, if I'm at a restaurant that expects a tip, I am nearly always going to give a 20% tip unless the service is really subpar. Some people would argue that's too high, but I've been out with one too many people here who have a "well, the waitress took too long to get my check to me or misread a menu special item, so cut her tip in half" attitude.