I agree. Slavery was never really stopped. Big brands like McDonalds use convict labour. Some states will lease a slave/convict to private citizens for things like yard work.

Why would people that benefit from forced labour want to end it? Cheap labour benefits the wealthy - more money to make money with. And to those who think criminals should face actual punishment and pay back society - well: Why would they have a problem with forced labour. And, we have the political spectrum nicely tied up there - at least a majority of it.

If you want to get reform in: You need to address two groups - the "tough on crime" crowd, and the "abuse of prisoners is unacceptable" crowd - and that CAN be done. We need some core changes:

1. Restrict Solitary Confinement to violent outburst - and restrict it's use. After all, our goal is to encourage people to participate not drive people into nonfunctional insanity.
2. Create base rate pay that is tied to minimum wage (like 2/3's of it) with 1/3 going towards a savings fund, and 1/3 for the individual to use on whatever is allowed for them to buy. In effect: There should be a reason to work.
3. Increase base rate of repeat offences BUT tie in a labour + rehabilitation program participation as a way to reduce that sentence across the board.

Those three things - increase penalty for uncooperative individuals; It creates an environment of owning responsibility for actions; and it means that prisoners aren't being paid a fraction of the minimum pay rate of the 1960's. We can go even further with this:

1. The 2/3 of minimum wage is for low security prisoners.
2. Medium security prisoners have a lower rate of pay - say 1/2 of minimum wage, with the difference going directly towards restitution costs.
3. Violent criminals and high security prisoners gain no rate of pay for 10 years or until restitution is fully paid - whichever comes sooner, and their pay rate is 1/3 of minimum wage with the difference going to restitution costs.

In this way: There is a STRONG incentive to take actions, and efforts that will get you transferred to a lower security prison. We can also do things with half-way houses - and support training programs, and perhaps even voluntary association with a case worker post conviction for individuals that FEEL like they need extra support avoiding re-offending. This is not about reducing, or removing the existing system - but expanding it.

In effect: This entire set of changes is not about reducing the punishment on crime, nor straight up reducing the incarcerated population. Instead: It's all about PERSONAL responsibility. And maybe, you could actually get THAT kind of reform through.