See, everyone reads Nurse Ratched wrong. And in the book, we're seeing her through Chief Broom's eyes; in the movie, through the sleazy criminal's.

Remember that everyone except Jack Nicholson and Chief Broom were there voluntarily. They signed their own selves in, which means they can sign their own selves out pretty much any time they wish (as long as their doctor deems them harmless to themselves and others.)

But when someone else - such as the police, or the courts - sign you in, you're in until they damn well decide to let you go. Chief Broom had serious mental issues (he thought everyone else but him was some kind of robot), and was actually dangerous. Ratched knew this.

She also knew that McDummy was sleazeball repeat offender who was trying to abuse the system; no mental illness, just a petty criminal jackass typical hippie of the sort we're seeing still. I have known people like this, they just don't care, and they keep this mentality well past their 40s.

Ratched is mostly working for the salvagable ones, the ones who checked themselves in - the ones who WANT to be helped. And part of that help is keeping them on a kind of schedule, and I don't think I can explain properly just how important that is, when you're not in a position to take it for granted, and you're basically left on your own devices ...

Her job was simply about as thankless as a drill sergeant's. And if you're rooting for Jack's character, you're rooting for the wrong guy. He's a villain protaganist.

That being said, there's no defending lobotomies and shock treatments, but as I said, those were already been legislated out. But keep in mind that psychologists usually have their own pathologies that run towards "cruel streak", look at what they do to non-humans, ffs. They love shocking living, feeling beings.