Earlier quoted context omitted.
Why would workers from Eastern Europe not have passports? "Eastern European" typically means EU-member states, with Ukraine being the exception even before the war (within reasonable distance, populous enough for recruiters to go to). EU-citizens don't need a residency permit, and they have access to the social system in Germany. They're often not informed about their rights and that should be improved, but "they end…
This story doesn't pass the smell test. Appears OP is from the netherlands, not a friendly country towards east europe, but I still don't see how people can end up on the streets in a country where by law they have equal rights (or is very cheap to return to home countries, and sue the abusive employer).
1. Don't speak any language other than your own, especially not the one spoken in the country you are planning to work in.
2. Get your work and accommodation organized by the same company or person, trust him when he says that you need to pay X amount upfront for the accommodation, but you will get it back eventually.
3. Give your passport to the organizing company or person, so you won't accidentally lose it (if you have a passport at all - moving within the EU does not require one).
4. Do not request a contract, or sign it without understanding what is in it (because it is not in a language you understand).
5. Be in such a desperate financial situation that you cannot just travel anytime you want, let alone find another accommodation.
6. Even if the circumstances are troubling (living in a small apartment with 10 other people, working and not being paid after a month etc), do not go to the police, partly because you don't speak the language, partly because you don't know what rights you have, partly because they can kick you out of your job and accommodation if you complain.
7. For younger girls the steps are a bit different, and much more evil. Let's not get into that.
In a way, the EU being a single job market makes these kinds of things even easier - no real control of who enters a country, who lives where etc. In theory, you must register your change of address, social security etc. In practice, the system is easy to exploit.