Answer:
Slavery was used for forced labor, with the benifit of economic gain. Many prisons force their prisoners to do manual labor, like cleaning litter from highways, mining, and even construction in some cases. So the prison industrial complex is fairly identical to slavery.
Step-by-step explanation:
Slaves were forced to do labor without pay, and prisoners are paid in pennies for each hour of labor they do, which is just barely enough for them to pay for food and other things in commissary. (like a sort of shop in prison where prisoners can buy things like candy, coffee, toothpaste, etc..)
I hope this helps :)