I've been running into a lot of these US-only stereotypes recently that I was never aware of. They kind of make me sad. I don't really get the point of tipping. In my country servers are unionized and paid decently, meaning they don't have to rely on untaxed income. It's a nice gesture, but by no means expected.
It varies massively across the country and in most places servers are excluded from minimum wage laws. The federal minimum wage for servers is $2.13 an hour, with the expectation being that tips will get them up above $7.25 per hour (and that the employer should make up the difference if they don't). Some states have higher standards than this. $7.25 an hour with a 40 hour work week comes out to about $15,000 a year and of course a lot of these jobs don't offer any sort of healthcare benefits. Edit: I was curious to see what the actual average is opposed to the minimum. The Bureau of Labor Statistics puts the average annaul wage at around $20,000 or $10 an hour. This data does include reported tips at least.
It's funny you should mention that since the most common stereotype I heard while working in food and bev (in the US) was "Europeans don't tip." I never noticed any trends with any so-called groups, but I also never focused on it. cgod is right about tip income being taxed as I knew several waiters who were audited by the IRS. This was in the 90s so hopefully they have moved on to bigger fish.