E.g. 'stealing someones identity' is a thing. Where I live, SSN and driver licenses are public record (you can get a photo copy of anyones driver license), so they are unusable for fax scams. Having a system built on such items being 'secret' is probably a culprit.
IIUC, telecoms in DE charge the originator of the call for call completion, while in the US, telecoms charge the originator and the recipient.
As such, US telecoms have a vested interest in completing scam/spam calls while that is not the case in DE.
I may be misunderstanding this, so if someone more knowledgeable could comment I'd appreciate it.
On the other hand some (legitimate) support call centers are located in Eastern Europe so it's possible to find enough German speakers there (although not native ones).
Zero ever on my mobile phone (and I know the number has been leaked by at least one breach).
Maybe 1 per month on the landline of my parents and these days it's exclusively "Microsoft" trying to "fix" their computer (weirdly enough with an English speaking scammer).
Either Germans are not a valuable target for "legit" companies or some regulation is working it's magic behind the scene.