The ACLU, using from the Bureau of Justice Statistics, says that "for-profit companies were responsible for approximately 7 percent of state prisoners and 18 percent of federal prisoners in 2015"

I don't think that count's as "highly" privatized. I personally think the incentives involved in the private prison system present major ethical issues, but I think we need to look at the incentives involved with the our legal system and governmental prisons, also.