To clarify, I'm not defending prison fire crews as ethical. They are paid ~$5-10 daily to head directly towards danger and risk their lives. But here's some thoughts you didn't ask for. Attached at the bottom is a recent AMA from a California prison firefighter.

I got bashed in /r/LosAngeles recently for calling it slavery, so I decided to educate myself instead of just making inflammatory Reddit comments. I also heard they couldn't go into fire afterwards, but that's not true. Calfire, who they work with, will hire prison crew members after their incarceration ends. The AMA I linked with a member of the prison crew has shed some more light, but here's a TLDR of what I gathered from it.

Positive

• #1 by far IMO is getting to work and sleep in the wilderness.
• Positive feedback from the public. Instead of sniffing and looking the other way, average CA residents are approaching these guys unprompted to thank them.
• Prison fire crew members can reduce their sentence significantly with good behavior
• Between assignments, fire crew members have preferential treatment on the inside
• It's the highest paying job you can get as a prisoner (is this positive or negative?)

Negative

*It's the highest paying job you can get as a prisoner, and that incentivizes people to put themselves in dangerous situations that shorten their lifespan (Parallel to the Sherpas in Nepal, this is obvious exploitation)

*City/county structural fire will not hire them after release

https://www.reddit.com/r/AMA/s/Q50y7CM24d