The fact that is not widely advertised is that servers are entitled to the state's minimum wage. That's the same minimum wage as the guy in the back washing dishes or the guy in the kitchen makes. Yes, employers are permitted to pay wait staff less at first. However, if the tips and the lower hourly wage don't average to equal the state minimum wage, the employer is required to make up the difference.
At the Chinese Restaurant that I go to that has a Mongolian Stir Fry there is a jar on the counter to put money in for the chef who does the stir frying. I never put money in the jar because the chef is being adequatly remunerated financially by the restaurant for services rendered.
Tipping basically says, "Young Man, with this dollar bill you too can build an empire like the wealthy businessmen before you who started with as much in their pockets." The tip is a symbol of economic prosperity.
It makes me mad that you're not supposed to tip union grocery store clerks for packing up your car. I always slip a nice young kid a couple of bucks or so anyway. They performed a service and I want to show my appreciation, and the unions can pack sand.