They are "forced" to work at below minimum wage rates both for the government and individual firms in public-private partnerships.

I use "forced" in quotation marks, because although prisoners are no longer forced chain-gang style, these jobs can be a prisoner's only source of money, which is required to purchase communication with the outside world.

In some states (e.g. Texas) prisoners aren't even paid any wages--they're just punished if they refuse to work.

An article about this: https://truthout.org/articles/unpaid-labor-in-texas-prisons-...

Is this work economically valuable/worthwhile to whoever is employing them? What are the profit margins that their employers make from their prison labor?

Near where I grew up there's a state prison called Angola, built in 1880 on the site of an old plantation called Angola. The slave quarters were repurposed as the original prisoner quarters. Mostly-black prisoners raise cotton and other crops for pennies on the hour, overseen by mostly-white officers called "freemen."

https://ccnmtl.columbia.edu/projects/caseconsortium/casestud...

https://en.wikipedia.org/wiki/Louisiana_State_Penitentiary

If you're sincerely interested, I found the documentary "13th" to be informative and thought-provoking.

https://www.netflix.com/title/80091741

Last Week Tonight on Prison Labor: https://www.youtube.com/watch?v=AjqaNQ018zU