>> Private companies have a greater motivation to maximize profits than public entities do.

Corrections officers unions have strong motivations to keep prison populations high as well and unions tend to be stronger in the public sector than the private sector so its not obvious that private prisons increase the aggregate political pressure for high prison sentences.

http://mic.com/articles/41531/union-of-the-snake-how-califor...

>> The problems stem from that.

This seems like a serious inversion of cause and effect. Our problems with prisons pre-dated the growth in private prisons and private prisons remain a small fraction of the overall prison industry so its hard to see how private prisons could be the primary source of the problem.