when I was waitressing in Oregon in the 70's the tax law had the establishment figure 8% tips. Believe me, there are lots of places where you'd never get that much in tips. Buffets come to mind, and fast food..I mean who do you tip there? Maybe they do fall under the minimum wage law.
I've also known a few waitpersons from high end restaurants who made what seemed like a fortune to me, 2-4 hundred a night.