If you can’t afford something you shouldn’t buy it. Just because you don’t agree with the system doesn’t mean you get to ignore it and then justify it by taking a moral high ground.
You know the servers wages are dependent on tips and you choose not to pay them. THAT is the social contract. Whether you agree with it or not.
If you cared about changing the system you’d take steps to change it without screwing the workers. You’re just being cheap.