Regarding the “why is this so popular in prison and not outside”, I think calisthenics are great if you have lots of free time and limited access to specialized equipment, but outside of prison, people are mostly looking for aesthetics with minimum time needed. At least in my experience, getting big muscles is much faster and easier with weights, probably for exactly the reasons this person doesn’t like them (for example, you can specifically target your pecs without having to strengthen every other muscle in your body first).
Regarding the “why is this so popular in prison and not outside”, I think calisthenics are great if you have lots of free time and limited access to specialized equipment, but outside of prison, people are mostly looking for aesthetics with minimum time needed. At least in my experience, getting big muscles is much faster and easier with weights, probably for exactly the reasons this person doesn’t like them (for example, you can specifically target your pecs without having to strengthen every other muscle in your body first).