Okay? This is well-known. What is your point?

> except as punishment

So if making a profit is the purpose it is illegal?

And on top of that there are literally dozens of other exceptions the courts have come up with over the years. I was forced into slavery by the government in the USA, due to exceptions that allow the government to force unconvicted persons into labor in certain circumstances.

Here are a few of the other exceptions:

https://onlabor.org/when-is-forced-labor-consistent-with-the...