the main problem with US prisons isn't even that they don't rehabilitate people...most criminals are neurologically damaged and are beyond saving anyway. the problem with US prisons is that they actually make criminals more proficient at being criminals.
talking about actual criminals of course, not the massive majority of our prison population that's in there for selling marijuana or ridiculous crap like that. the fact that our prison system also turns harmless people like this into actual criminals doesn't help either of course