If you eliminate private prisons entirely and leave everything else alone, a pitifully small proportion of the people wronged by the criminal justice system would even notice, let alone receiving fair recompense. It's not so much that they "should not" be fought against, it's that it barely matters. It is simply poor allocation of attention.
Forest, trees, etc.
I'm pretty certain it matters to the 20% of federal prisoners, and 7 percent of state prisoners in those prisons.
I take thatswrong0's point to be that you would likely find as much if not more corruption in the federal, state, and county prisons and jails as you do in private prisons. And I'm quite sure that's the case. Inmates are just too easy to take advantage of. They can't really complain to anyone and nobody (for the most part) cares.