The determination of whether a job is useless is largely left to the person responding to these surveys. If a person thinks their job is useless, then it is. They may be right, but it's also possible that there is a disconnect between their perception and reality. The study uses the example of doormen who are considered to provide no useful function except as a symbol of prestige. However, I'd argue that if the doorman viewed themselves as that symbol rather than a necessary skill which facilitates ingress and egress, they may feel differently.E.g Vanna White isn't a letter flipper (useless), but an entertainer who flips letters as part of her job.

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.