I myself have never been in “prison”, however, I know lots who have been. Some of the things I learned:
You can get anything in prison for a price. Often, favors are paid on the outside of jail. For instance, you do someone a favor on the inside, and they will sometimes send money to your family or gifts to your family. I.e., my brother in law once had a “friend” who was in prison with him, send me two beautiful evening gowns. 
The prison and guards do not care about the prisoners. My brother in law has told me that there are over 10 prisoners where he is, who have Alzheimers. He told me it was terribly sad, that they did not even know where they were, yet were still kept locked up.
I have also been told, that when in jail, prisoners do not share their stories, like portrayed on t.v. It is considered “bad manners” to ask a prisoner about details to a crime. Most prisoners really do not care anyway.
Despite the believe that rapist and child molesters get whats coming to them in prison, 99% of this is not true. They keep offenders like this together, housing the abusers in a separate unit. And they are very carefully monitored, so it rarely happens that they get a beatdown or something worse.
I have also learned a lot of peculiar things about prisoners over the years, as various family members of mine have done time. I know one family member that actually would get cigarettes from the guards, and she has funny crazy stories about her times in the pokey.
Just thought I would share. I find prisons and prisoners fascinating, and I always ask lots of questions.
Just one other fact, almost all prisoners gain weight when they are in the klink. You may think it is because of lack of exercise, however, it is mostly because the only food they are allowed to purchase from the canteen are all carbs. Cakes, cookies, pasta, etc. , and because most of the meals served where high carbs.