Except the food cost is only a small part of what we are paying for at a restaurant. What we are paying for is the worker's time and skills. We could, mostly, eat the same ingredients at home for much cheaper.
A lot of the other costs are small and make profit in scale.
In this case wouldn't the cooks time and skills be more important? Almost anyone can carry a plate but it takes a more diverse set of skills to cook various meals in timely manner while trying to prepare another 10 orders as well.
Not to say the server isn't important as well but tbh, I'd rather have shitty service and great tasting food than have amazing service and terrible food. Ideally great food and great service, that will defintely get me back.
Sounds like a broken system where workers are being exploited. The operating costs of everything should be pirced into the food. Customer's shouldn't be expected to subsidize wages.
You undervalue good service. Good service, like good cooks, keep people with allergies from dying. Who exactly do you think passes on the allergy information? In a more general manner, good service makes sure that your order is presented the the kitchen staff correctly and matches expectations when they say it's ready. It's not just about whether or not they have a pleasant demeanor.