It‘s perfectly legal for the banks or companies to send a bailiff in such a case and seize your property to pay for your debts.

Not in the US. Although a lean could certainly be imposed by a court, you don't have anything to place a lien against when you're poor.

So, how do creditors protect themselves against fraudulent debitors?

If someone owes me money in the US, I don't have any means to send a legal request?

I Germany, I can just go to court without needing a lawyer and the court will eventually send a bailiff if my claim is justified.

You're out of luck. That's why we are so reliant on the credit reporting agencies. There is some recourse if you already own assets. There are two types of loans. Secured and unsecured loans. Secured loans are backed by assets and those certainly can be forcibly removed. Unsecured loans (the vast majority of smaller credit card type loans), have no backing and the lost money is generally understood to be recovered through interest payments.

I was young and desperately poor. I had medical debt. What were they gonna do, seize my kidney?