8%, or 1 in 12, prisons being private isn't that encouraging when blowing up the statistic to the scale of a country. That's still thousands of facilities with perverse incentives.

But yes, the ones really profiting are those making deals to service the prison. Those who bring food, or repair the infrastructure, or custodial duties. A lot of seemingly unrelated industries have every reason to lobby in the background to focus on "hard on crime".