Everett M. Greene writes:

It would seem that the German position is rather extreme
in that the people on a given aviation frequency have no
expectation of privacy (and, for the most part, couldn't
care less). Taken to an extreme, it would seem that the
German equivalent of the FAA can't record ATC transmissions
and use them for quality control, training, or violation
proceedings since uninvolved third parties will have been
recorded.

In Germany, everything is forbidden, except that which is permitted.