We saw all this before after civil war in the south charging “no body” poor blacks and whites alike with bogus crimes to provide “free” labor, didn’t need minimum.
The difference in private and state is the corruption gets institutionalized on a much larger scale it sounds like in the private system expanding the profit taking beyond the profit bonus incentive with contractors to corporatized institutions where a whole host of third parties profit from it. Both are easy targets for corruption no question.
Regarding the conservative free market conflict with private prisons only one thought. It has been accepted in US public/private institutions that some institutions are best administed by the state. Arguments vary as to validity of prisions returning to a purely state administration, theoretically public oversight of state institutions should be closer to the ground but this is not always or ever true.
This presents the argument that in a republic administration of entities should always be kept as close to the local citizen as possible. It Joe Blow witness first hand corruption and there are hundreds of joe blows calls for correction might come sooner. That means joe blow has to be educated and give a crap though and that is a problem in America today.