Not the OP, but I'll take a crack at it. The problem is that creating order (or, more generally speaking, rehabilitating unorderly parts of society) and making

Not the OP, but I'll take a crack at it. The problem is that creating order (or, more generally speaking, rehabilitating unorderly parts of society) and making money can sometimes be adversarial processes, thus creating a conflict of interest. Since it has become profitable (for private jails/prisons) to put people in jail and keep them in jail, there is a clear incentive to punish lesser crimes more severely and to not rehabilitate jailed people fully with hopes of them becoming a repeat offender. Therefore, the problem is that privatization of the criminal justice system is at odds with what a criminal justice system should hope achieve: order, appropriate punishment, and rehabilitation of those who break the law. In fact, I would argue that it incentivizes almost the exact opposite.