Ok, we can all agree that until a high level of automation is achieved, such jobs are necessary.

But how many of the people defending the need for such jobs would actually want to do them?

Usually they're happy to let other people do them, but would balk at doing them themselves.

This is especially true for "dirty" or "unsavory" jobs such as garbageperson, exterminator, food processing / slaughterhouse worker, etc.

People are usually happy to hire such people or consume their products, and talk about how essential they are, but would never want to be one themselves.

On top of that, they'd usually look down on people with these jobs and never dream of associating with them or inviting them to their parties.