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.

The way I see it is that the company is already withholding pay for this situation to even exist.

Americans are being led to believe tipping is the only way "unskilled" low paying work can exist. Yet these companies often make money hand over fist. They'd just make less money if they had to fairly pay their staff. But Americans seem to look down on the workers that do these roles, so companies get to exploit them.

If you're salaried, imagine your boss randomly said to you "Sorry, I can only afford half your salary. But you can ask our clients if they could graciously donate a small percentage of what they're paying for our services. Hopefully it makes up the difference." You'd be furious! You wouldn't agree to such a change. So why agree to it for food service workers?