Since a move is tracked by the „Bürgeramt“ they will find you since this is a jurisdical topic.

About ten years ago, a friend got such letter about 700€ and they argued that the wifi was public (hotspot mode) and they did not know who did that.

Besides, those are the reasons why torrents are nearly dead in Germany as far as i know.

I am not too deep into the scene, but i could imagine that this is not neccessarily desired since every signed release could be linked to them from a forensic and juristic perspective. (in the case they are arrested)