When the system suddenly has a MOTIVATION to have more prisoners, it gets dangerous.
When a warden's paycheck bonuses reflect the productivity of his prison work force, you suddenlu have a man in power with a motive to fudge things to keep men in longer and working longer. When a warden's paycheck reflects the number of organs harvested from his prison, he has a great motive to let health care slide or put people in positions where accidents/injuries are more likely to happen.
You can say "no one would do that" but that's incredibly naive. Thils 98% probably wouldn't, there are always the 2% who would turn their prison into their own checkbook using human capital.