2) They wouldn't have to if they didn't insist on locking him up
Even though the enrolled people are completely trustworthy, doing this prevents untrustworthy people to simulate interest in the program just to be able to contact the external world for illegal activities.
List of prohibited items: https://www.law.cornell.edu/definitions/uscode.php?width=840...
Framing it as offsetting the cost would also make it very easy to increase the cut, bit by bit, until it gets to a truly unreasonable level. And since the person is already in prison and we have to pay for them no matter what, why would they choose to work if the deal is so bad?
This is a state by state thing. FWIW in this case, ME doesn't have private prisons. I don't bring this up to imply everything related to their cut is on the up and up, however, I believe Maine is very much incentivized to make this a useful program in terms of keeping people from returning to jail (as opposed to squeezing every dollar from the prisoners).
And to be clear, I'm opposed to capital punishment and dangerous conditions in prisons. I'm just pointing out that I don't think your argument is very good. If you think we as a society are willing to flippantly put people in prison because it's cheap I don't see how you can trust us to no resort to other flippant measures if the cost was high.
No, they forfeited their freedoms and we're put away by due process, but if that's your point of view then we've nothing further to discuss. Incredible stuff on HN these days.
> Why are they paid
Because people have expenses other than food and lodging. Prisoners do to, some save money for after they leave prison others spend it at the commissary.