I think this show was a pretty good representation of how prisons are based on my research. While studying architecture, my thesis topic was Juvenile Detention Center. For that, I did research on both, Juvies and Prisons.
So basically, most crimes are circumstantial, not intentional. That means not all criminals are psychopaths out for everyone's blood. Murder and sexual offenses are the worst types, but murder can be circumstantial, mistake, or self-defense, whereas sexual crimes are always intentional. After that other crimes are of lower degree and may not always mean the person involved is evil or have no moral code.
As for the fun part, prisons get to interact a lot in jails, only difference being, they are in general separated by the severity of the crime to reduce conflicts. Most prisons will form or join a group to survive in case things go sideways. They get to learn new skills and even get proper education including diplomas, PG, and master's.
What was lacking?
1. They should have shown counselling sessions. Most prisons have one on one counselling sessions with a professional to improve their mental health, help them cope with life inside, and prepare for the outer world before they are released.
2. Lack of sensitivity towards drug addiction. When a person goes in for drug possession, if they are addicted, they are moved to rehab first instead of putting them in a normal prison.
3. Freedom to move out and about whenever they felt like it. While jails are interactive, they still have set time to let prisons out of their cells. Most of the time, they are not allowed to get out of their cells after sunset.
Lastly, I want to say Je Hyuk's control over the prison guards and employees but even I know that celebrities, politicians, and popular people have a lot more sway in prison. So, it was like accepting a bitter truth.