We imprison more of our citizens, and for longer, than just about any civilized country. They are mostly black and brown men. Some of them are dangerously violent. Some would steal our property. Many are there due to drug offenses. A few are political criminals and tax cheats. Every one of them is living on the dole. We pay for their food, lodging, health care needs. We pay for some types of education, make sure they have religious services, and give them a chaplain, a counselor, and a social worker. Usually we do these things poorly and grudgingly, but we don't do them at all for the poor non-criminals on the outside. In my state it has become nearly impossible for the poor to get mental health care. Unless they are in prison. Vocational training? Forget it, unless they are locked up.
Turn them out, the non-violent ones, and put them to work. Let them earn their bread by labor like the rest of us. Give rapid parole, but with severe penalties for those who decline to work. The state can provide infrastructure jobs and pay the parolees part of what it would have cost to keep them inside, and keep the rest, or spend it on close supervision.
Most lawmakers know the prison rarely rehabilitates and that sentences have become ridiculously long, straining budgets. They also know that many of their constituents like all those criminals, especially the black and brown ones, being locked away for years and years. So they have to paint themselves as tough on criminals. No matter how much it costs us. No matter how wasteful it is.