Yeah the US's definition of human trafficking is...not good. Like if this was on a much larger scale, it wouldn't even be illegal. JP Morgan Chase hiring thousands of visa workers and paying each one $10k/year less than comparable American-born employees? That's just the system working.
And that $10k reduction in pay is essentially the result of them holding deportation over your head. If the threats are made via boilerplate contracts then it's good and legal.
Yeah but where do you get the vitamin C? Isn't half the problem that it breaks down easily, and fruit can't be kept fresh for very long?
It's questionable whether this knowledge will spread or persist that well. The British navy figured out how to prevent scurvy and then forgot again.