Guest, I don't know what country you're in, but in America waiters are not paid a living wage. Tipping for decent service is a social requirement like wearing pants in public. Essentially, you're paying the waiter for a service because the restaurant's prices do not cover it.
   As for waiters being addicts, I can say that about half the people I know have worked as waiters at some point in their lives, and none are addicts. Even if they were, it wouldn't matter -- when someone performs a service for me, I pay him- you can't use the possibility that someone might misuse his money as an excuse to rip him off!