Ya know, dollar for dollar, I bet pizza is responsible for more productivity than any computer.
Is it? Many of these places are serving WAY too many calories, in arguably questionable conditions, and relying on minimum wage labor to make it. So you're being paid to help other people pay to get fat.
I think it should be okay to recognize that a job has no real value except generating income for the owner. If the owner cared about the work, he'd be right there next to the workers.
People sometimes want pizza, and they're willing to part with money to get it. It's not deeper than that. The social value from a pizza job is in the vibe between your coworkers cursing the entitled customers, and the occasional good tip. Many people who work food service are down on their luck, drug users, or recovering druggies. Looking at it through a social lens, I would see this as the capital class exploiting the poor for income and furthering their suffering.
Most jobs are bullshit. There are some that are supremely important, but most could be replaced or outright forgotten, and the only problem would be "We built a system assuming everyone was forced to work and support themselves, whoops." Humanity is slowly creeping up to the point where everyone doesn't need to work, and we're not socially ready for it.
There was a recent thread where a person working for a pizza shop was depressed because he felt as though he should make a larger contribution to society than "just working at a pizza shop." From a career advancement perspective, this job offers little opportunity. However, from the social perspective of feeding the people in his area, it's immensely helpful.
Some of the fault for this disconnect belongs to their employers. Knowing the difference that they make in the world is helpful to everyone and something that companies rarely communicate.