Again, you choose to work where you're working. The 18% group tip is there so that the waiters don't get stiffed by a big party. It's a bit like insurance. Maybe you could have gotten 25%, or you might have gotten 0%.

I eat at sit down restaurants much more outside the US, and if the service charge is 10% or more, I won't increase it unless I think the service is extraordinary. I've given as much as a 500% tip in certain occasions, but it's quite rare.

I was in Saigon recently, and went to a number of restaurants that had a 5% service charge. They got a bit extra. I will say that it's quite nice to be places that the the service charge is reasonable (Hotels, restaurant, etc). That way I don't have to worry about tipping porters and bellman and so forth.

In most places being a server is not a lifelong career path. It's something you do while you're a student, trying to get a better job, or something you fall back on. You don't run into too many first graders who say, "When I grow up I want to be a waiter"!

Earning $200 for a 4 hours is a great salary. If you're made it your career, great, you're obviously doing something right. I'd guess that 80%+ would not want to do it for their rest of their lives.