OMG. I not from US and I never heard of this practice, but it's literally sounds like modern financial slavery.
Concerning Stieglitz, it’s unclear to me whether we owe non-contributing members their freedom. The federal USA costs a trillion per semester, so it’s 6400$ per year. Those who don’t contribute so much per year, are a weight upon the others. If anything, the actual-workers are slaves of the poor people.
Granted, social friction makes that it is not possible to make everyone contribute efficiently. But we owe them money only because the society is not perfectly organized, not because they’re poor.
As for the slavery induced by the prison IO system, it is obviously inhumane and we should repay the victims probably a few hundred dollars per day in jail.