Even though there is a lot of hard, unpleasant work I think you would find most of these inmate fire fighters appreciate being out in the great outdoors--vs being locked up in a cage (a prison).

It's hard and unpleasant. It's also dangerous, involuntary, and effectively uncompensated.

Job training can contribute to rehabilitation but most former inmates will never be able to work as firefighters because of their criminal records. This is exploitation of a group that is taboo to defend.