Why would a for profit prison system want to rehabilite anyone?
If the prison population dips below a certain point, they don’t get as much money, it’s literally in most contracts for prison services that the prison must maintain a certain number of prisoners.
The easiest way to keep them full, is to add charges for people already in prison. You do that by making their lives hell and putting them in situations where even a rational person would become stressed and prone to violence.
Even if they get out, they’ll be back.
Tldr:
The American prison system is designed for the opposite of rehabilitation.
It’s designed to maximize profits, and that means maximizes prisoners.