No, it is because if all the janitors “went away”, everyone else can pick up the cleaning supplies and continue cleaning.

Supply and demand.

If all of the people who could be janitors went away, there would just be nearly no people. Being a janitor isn’t really a special skill.

Surgeons are over paid, garbage men are under paid.

Except that should you need surgery, you'd care who the surgeon would be, but not who would be handling the bags of medical waste.