I lived in Germany for 30 years and never had used a paper check before I came to the US. What are they used for?

Insurance companies and paper magazine publishers like using them for payouts.

I know an eccentric person that also uses them. When I cashed such a check the eyes of the employee lit up and it was shown around among the tellers after asking if that's ok (which is a bit out of the ordinary as they usually act very discreet and professional) so I'd say that's a rare thing.

They are used in France a lot. I bought my car with one, and my family doctor only accepts cash or checks.