When I waited in college this sort of thing happened all the time, but that's kinda beside the point. I guess to me it's weird that tips convey a sense of whether someone "deserves" their wage, whereas there's nothing really dictating why a waiter "deserves" their money more than the cashier at a grocery store. Minimum wage jobs are minimum wage jobs, so is there a particular reason for the custom of tipping (beyond the usual "tipping helps a subset of people make more than minimum wage").