[cryptoz]

That paper is older than 20 years, and takes place during a short period of time in Florida, from a very small number of private prisons. A lot has changed since then, and the paper makes assumptions that are invalid with the current discussion, specifically the extremely small sample of private prisons (n=2?).

I don't think it's valid to draw concrete conclusions about the current crisis from the study you linked. There are far more variables at play than were studied in the paper, and those variables - such as racism, increasing societal inequality, etc - matter.

Also, reasons cited in that paper for the reduced recidivism are to do with the programs offered by the private prison. Are private prisons in all states / California allowed or incentived to offer similar programs? Do they choose not to?

These things affect the statistics, and drawing strong conclusions from that paper about private prisons in California today may lead you to invalid conclusions.