It's great that you visit people in prison.
Yet, perhaps you should listen more closely to the person sitting across from you in the prison cell, giving him more credit than being a gullible simpleton... Perhaps he knows something you do not. Perhaps your theology is a veil instead of a revelation.
Your explanation of our prison system's roots seems askew to me. Yet, I do know the administration of our legal system - and probably the legal system itself - has betrayed the word "penitentiary" which was supposed to be about becoming penitent and giving a person a chance for changing one's mindset and changing one's ways.
Tossing someone into a dungeon far from the light of day has been a constant method of dealing with the "criminal element" as long as there have been civilizations and even before! It is certainly not new to America!
A simple search will show other quicker - if not better - ways: immediate capital punishment (like stoning), exile (like penal colonies in Australia or worse - like in the movie "Papillon"), workhouses (like my own great, great, Grand Aunts - like any Dickens novel), poorhouses, and just plain abandonment from the tribe to fend for themselves(as in hunter/gatherer cultures)...
The right to a speedy trial has disappeared along with many other moral and rehabilitative alternative processes.
Perhaps because prisoners are a source of free labor for States that it is so easy for governments to give overly harsh sentences - consequences which are greatly disproportionate to the offense.
Yes. There are many drastic wrongs - sins if you will - being perpetrated against the "Perps' themselves...
Still and all, crimes deserve a response - punitive, corrective, medical, environmental or other.
America has plenty wrong with it, but don't blame God, Jesus, the Bible, the Gospel, or for that matter, other Christian Denominations...
By the by, there is not much of Christ in any Christian Denomination that I know of... So, there's that...
Still and all, iIt's good that you are trying to deal with this very complicated problem.