As someone who worked for years as a waitress in the US, even I have to agree with the sentiments above. I have read and heard many, many arguments for the system in the US ("we work so hard" - yes, it's hard work, but is it any harder than the job the dishwasher in the back is doing? no. And he's getting paid more, officially, per hour, but after tips you're making 3-5x more than he is!) but they are almost always justifying the fact that in the end, people who wait tables average a much higher per hour rate than any comparable job in the US. Yes, it's compensating for the fact that they're officially making 2.13/hr there. It's much more than compensating for that, actually.
whew, okay, deep breath.

Going off on a tangent there!
If you combine the required tipping in the US along with the fact that they're encouraged to turn tables every 45 minutes or whatever, it just doesn't make for a pleasant dining experience for me anymore. I am happy to tip for service, don't get me wrong, I was raised with it and have profited from it personally. But I find I enjoy the dining experience here (and on the continent) much better than I do back home now.
As for hairdressers- I often use the student college nearby. Their rates are amazingly low, and it leaves lots of room for a very generous tip (which they appreciate so much) when they do a good job. Which they always have (knock wood!)