Slavery is alive and well in most part of the world, especially south asia, middle east, Russia and Africa,where children with no papers are trafficked all the time for the worse things you could imagine. I'm not sure what convinced you otherwise.
Approximately two-thirds (about 61% to over 65%) of the 1.2 million people incarcerated in US state and federal prisons are employed in prison labor, totaling around 800,000 workers. These workers often perform maintenance tasks for, on average, 13 to 52 cents per hour, with many facing forced labor conditions https://www.epi.org/publication/rooted-racism-prison-labor/#...
There's also a very long history in America of laws and law enforcement being targeted against poor people and minorities. Vagrancy laws (https://en.wikipedia.org/wiki/Vagrancy#Post-Civil_War) and modern anti-homeless laws effectively criminalize homelessness, and the War on Drugs has had a major negative impact on poor people and minorities. Yes, in this situation those who have been imprisoned due to such laws did violate the law, but such laws, in my opinion, serve the function of kicking people while they are down rather than addressing the root causes of their poverty.
There's a good argument that having a system of convict labor creates a perverse incentive to fill that labor pipeline, similar to how well-meaning traffic laws (such as speed limits) can be abused (for example, "speed traps").
One of the side effects of a society tolerating thousands of people living in nylon tarps with no real safety net.
After USA destabilized Libya, it turned horrible. In Libya there are open slave markets. Adults. Africans trying to who travel a great deal trying to get to Europe are often kidnapped and kept as slaves in Libya.
https://www.humanrightsresearch.org/post/the-scandal-of-a-sl...