Also, the entire system is built around "justice", not retribution. People should only be imprisoned for as long as necessary to repay their debt to society or until they can prove they're no longer a threat to society (e.g. they've reformed), whichever happens first.
Seems to me if there is no real punishment, there is no deterrent keeping the person from doing it again as soon as they are released: "Oh wow, I trafficked women and all I got was a few years of psychotherapy in which all I had to do was smile and nod? That wasn't bad at all, I have no remorse, and I'll do it again, this time learning from my mistakes so I don't get caught!"
For example, John Newton was a slave trader before finding God, becoming an abolitionist, and writing "Amazing Grace".
The Apostle Paul was at least an accessory to murder before his conversion.
I'm sure that there are examples outside of Christianity. That's just my background so its what I know.