Well if the people working the fields requested to be on the detail what is the problem with it?
I think the experience of an honest day of work would be good for them. Maybe a nice meal beyond the crap they normally get in prison for a hard days work?
The prisoners doing this have a choice.. the other choice is being locked in a cage the size of your bathroom for 23 hours a day. Of course they'll do it, they'd do it for free - which the 40 or 50 cents an hour they actually pocket essentially is.
It effectively puts slave labor into competition with free labor, distorting market forces. It creates a pool of sub-minimum-wage workers that politicians can use to reward cronies. It distracts prisons from their core functions of protecting the public and rehabilitating offenders. It creates an incentive for prisons to hold on to the most profitable inmates, not the most dangerous.
The history of prison labor for hire is not a pretty one. From Dickensian debtors' workhouses to leased black work crews in the post-bellm South, it is a system that invites abuse. It is not a camel's nose that I want to let into the tent.
I have no problem with work as a condition of incarceration -- the state has plenty of jobs that need doing. Georgia is second, I'm told, after Texas in its use of prison labor -- they perform landscaping and maintenance at state parks, make and bottle cleaning products for use in state offices, build and repair furniture for state offices, and of course perform the classic duties like picking up litter on the highway and stamping out license tags. Running printing presses for state printing jobs. Tasks that both benefit the state and give them skills for when they get out.
When my dad worked at the prison in Buford, GA, there was one good ol' boy who took the work crews out each morning. They weren't chain gangs in the sense that they weren't chained to each other, but otherwise it's pretty much the same vibe. This' good ol' boy had the same routine day after day, with little variation.
"Men," he would say to the prisoners lined up alongside the reinforced school bus, "The state tells me if one of y'all tries to run, I am expected to fire a warning shot."
Shoosh-BLAM! as he racked his 12-gauge and fired it in the air.
"That was your warning shot. Get on the bus."