I actually have two main sources, plus tad bits that I've learned just researching on the internet.
My first source is one of the Adam Ruins Everything episode on the American Jail systems.
Jails aren't run by the government anymore. Jails, or prisons are money making machines. The government gives them OUR tax money, to keep pretty much innocent people in jail. Why do I say innocent? Because the private jail systems have a minimum amount of people that have to be in their jail. Which means once you enter, they'll keep giving you years for "bad behavior", such as not wanting to mow the lawn for 10 cents an hour.
My second source is a documentary called the "Thirteenth".
Jail systems aren't meant to be places of "rehabilitation". Do you know why? Because back in December 1865, when slavery was no longer legal, former slave owners still need workers to keep their plantations going, but didn't have the money to pay... so here comes our wonderful constitution to the rescue!
The Thirteenth amendment states, "Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction."
AH HA! See, right there, "EXPECT AS PUNISHMENT FOR A CRIME.". That little loop hole made it so that anything a black, yes a black, person did was a crime. Even accusations that weren't true could land them in jail, and back as a slave.
So if you connect the dots right now, the goal of the overarching prison system is not, and was never about "rehabilitation".
Now, I still have some more to say on this subject. Even if you were to ignore how our wonderful prison system got started, there's solitary confinement to think about.
Solitary Confinement makes people insane. Once one person goes in, and then comes out a completely different person than they were, they're an example to the others.
If our government and our jail systems want to rehabilitate people, and help them enter the work force, and of course, stay out of crime, making people unable to care for themselves is not the way to go.
I hope this helps, and sorry for the long answer.