Not to mention the Federal prison Industries https://en.wikipedia.org/wiki/Federal_Prison_Industries Revenue $531,453,000 (2019) "Under current law, all physically able inmates who are not a security risk or have a health exception are required to work, either for UNICOR or at some other prison job.[4][12] Inmates earn from US$0.23 per hour up to a maximum of US$1.15 per hour, and all inmates with court-ordered financial obligations must use at least 50% of this UNICOR income to satisfy those debts"

And that is just one of them...on the federal level...not state.