I'll preface by stressing again that I think everyone should be paid a livign wage, and not need to supplement it. That said, I hate the principle of automatic tips.
Maybe its because I am a Brit, but to me, a "tip" is something given for extra-special service. Something over and above what I would regard as the bare minimum of getting what I ordered to my table, or stopping the cab at the place I have just paid to go to.
But with a requirement for automatic tipping, I can't do that. When I last went to the States, the advice in the travel book equated to pretty much "unless they dump the drink in our lap, you shoudl still tip 12-15%". What the &%$@? That's NOT a tip. That's just an additional cost to the stated price of your drink or meal that you have to pay whatever. Frankly, I'd rather every restaurant and bar put their prices up by 20%, passed the increase on to the servers as additional wages, and left me to decide if the service I got warrants leaving some extra cash. If I'm paying it anyway, lets add it to the prices and stop calling it a tip - because when it is damn near obligatory, and always expected, then it ISN'T a tip: its a charge.