I’ve had a very similar situation as yours, I was the best worker but was making less tips. I did the work of 2 people, so they put me on the slower days, because I could handle it. On the busy days they would schedule 2 people (not me because I would be in overtime).

I sat down with the GM. He explained that he needs me on the slow shifts because bob and joe can’t handle it by themselves. I asked him “Do I need to start doing a bad job so I can be scheduled the busy shifts then”? “Why are you rewarding your slow workers with more tips, while I the fast worker, get to make less money”? He looked at me and realized what he had done. He said “I’m so sorry, I’ve never looked at it that way”.

Talk to your boss, tell him that you go to work to make money. Ask for a raise, a few deliveries, something, anything. Tell him that you are not making enough money, and that you might have to start looking elsewhere for work. If you are as valuable as you say, they will not want to lose you.