This is exactly what was said to my now former (I wonder why??) Co-worker when he asked our owner about raises. The only problem is, is that it doesn't matter how good your attitude is, how many add-ons you're able to sell, or how efficiently you're able to work, some people will NEVER tip.
Even on some of our busiest days where I give my best, friendliest, customer service, there will be little to no tips.
It's a slap in the face that both of my store managers can drive high end cars but yet I have had to go at least a week at a time with nothing to eat, because I have to rely on the kindness of tips. Oh, none of us are allowed to work any overtime whatsoever to compensate, but the managers can work as many overtime hours as they want. Even though we carry their asses and they're not NEARLY as efficient as we are, they still get to take in all the dough.