its just people underestimating what people do in their actual jobs. Every thing has a huge long tail of work. things like 'accounting' is obvious but there are entire jobs around just buying stuff, around logistics, around fleet management, around managing your staff (HR), there are LOTs of specialized roles and they're not all dumb because you think they don't do anything.
Even in accounting there are many roles and subspecialties!
Even in accounting there are many roles and subspecialties!