The fair compensation for the service is the actual price of the service I have to legally pay. How the worker gets compensated for their work is not my concern. The service worker is employed by the restaurant for example, not by me just wanting to eat a pizza.

Tipping is an optional reward for outstanding service, and american companies realised their employees could survive (probably) on tips so they don’t have to fairly compensate their employees. If you have to ask for optional donations from people just to survive you are just a beggar, the fair compensation for your work needs to come from your employer.