Slavery as punishment is actually allowed by the constitution...
AMENDMENT XIII
Section 1. Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.
Just because it's legal doesn't mean it's ethical or moral, and there are enough examples of things in such categories.
Not just permitted, but actually widespread. If you’re imprisoned in Texas, Georgia, Arkansas, Alabama, and Mississippi, you are going to be doing unpaid forced labor which is slavery, and many of the prisons are privately owned.
Federal prisons pay roughly $0.12 to $0.40 per hour for regular jobs, which isn’t much better.
The hypocrisy of the US is breathtaking sometimes, and the current administration has the gall to criticise europe.
That doesn't mean it's right, it means the constitution is wrong!
The constitution isn't a holy book, it's some opinions someone wrote down on paper. Some of them might be wrong.