So if the prisoners aren't paid but the prison is, that creates motive to (have more prisoners|create more non-voluntary workers) with an illusion of volunteering because otherwise those non-voluntary workers would be involuntarily staring at a wall all day.
All fine and good until you're in that 1%. Then you might have a slightly different opinion on forced unpaid labor for someone else's profit, otherwise known as slavery.
But seriously, I see that 1% and it solidifies why prison populations should not be subject to forced labor for profit. That is not a low number.
Then it's not voluntary.