What happens if you Refuse to tip in America?

I used to deliver pizza. We remember who the good tippers are and the bad ones. If i have several pizzas to deliver, and one of them is for the one who previously tipped bad or not at all, guess who’s getting theirs last? Do I need coffee and a fill up on gas while on delivery and the delivery is for the bad tipper, we’ll guess what. I’m doing all that on the way to their house, not after. If it’s a customer I never had before, I give them the best service first until it’s determined they’re bad tippers.