> Or simply because the alternative is being homeless?

As I already mentioned, you can simply sign a contract and then proceed to ignore all the illegal clauses. They're not binding.

> And why should the default for foreigners be getting screwed?

People getting screwed because of them not knowing their rights is basically something that can happen in every legal system, and if people come from other countries without certain legal protections, they're more likely to not know about them. That's just a reality of life.