Are you being outrageous and arguing in bad faith on purpose?

I genuinely can't tell, in the event that you're not, nobody has ever suggested that janitors should be allowed to do the duties of brain surgeons. Furthermore, even if a single absolutely insane janitor decided he should be allowed to do the duties of a brain surgeon... nobody else would agree with them, because we live in a society with vaguely reasonable humans... and that janitor would likely be democratically FIRED for suggesting something so outrageous, or put in a mental institution.

Or are you worried about the janitor uprising in which janitors decide they can do all jobs known to man? Perhaps nothing can stop the janitor uprising, and we are all doomed.

Do you know any janitor that are willing to take the risk of killing someone and face the consequences of that? If so, I would recommend to keep your distance of that person.

What kind of idiot workplace would allow that? Perhaps if you don't assume the people you talk to are literally brain-dead, you might understand what they're saying.

what if they decide their duties are brain surgery?

In your world the only thing keeping janitors from doing brain surgery is the current corporate structure?

Like the nonsense a peer post to yours is spewing

Which parts are nonsense

but if your philosophy suggests that brain surgeons can get told what to do by janitors,

It can't.

Now, what do we do about brain surgeons and the cost of healthcare

The government pays for it like in most wealthy nations

You make my brain hurt.