There is a huge amount of protection for renters, a lot of things are simply illegal to put into the rental agreement and are automatically void. I really have no idea what you're talking about here.
Oh, and there are SCHUFA and debt collectors. Let's say a clause is invalid, but they gave you a bill with a due date. You can't ignore it or you'll get a bad SCHUFA or someone from a debt collection agency will knock on your door. This happened to a friend of mine recently ;( Then it's again your problem to prove that you are right. And it's once again a bureaucratic hell.
What if it's money you've already paid that someone won't give you back (while free or paid legal advisers tell you you're right)? It all ends with "you have to go to court". Yes, there is a chance that the other side will settle out of court. But usually they don't because going to court is a very expensive and long process and they don't think you'll do it (and most don't). And then it's just endless bureaucratic hell.
And if it's about the apartment, you've probably paid a deposit. And if you ignore some of the clauses, they will probably try to get back at you and punish you by not returning the deposit (or part of it). From here - GOTO 1 ;(
In which country is any of this different? Yes, if somebody is trying to scam you you may have to be prepared to go to court. I don't understand how else you're expecting a legal system to work.
But you keep insisting that there are rules to protect you. That's not true at all. Yes, there are rules, but you always have to prove that you are right/not guilty. In Germany the system is that you are guilty until proven innocent. You always have to prove that there's a regulation that proves you're right/not guilty, not the other way around. And you can't just ignore some clauses just because you think (or some legal advice tells you) you're right. You'll just end up with a lot of problems.
I've already given you many examples of how the system doesn't work in your favour by default, all the things that have happened to me or people I know in recent years. But if you want to believe in a "great" German system - that's your choice.
> 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.