[Mashimo]

I just looked it up. It appears the "stop people from playing cop" was my interpretation.

It is all about privacy.

Germany has very strict privacy laws. Probably because of our recent history in East Germany and the Stasi who systematic monitored the people. Similar to the NSA, but the state collapsed and people could read their own record. And a bit more "personal" because people where extorted to spy on their own friends and family. Movie suggestion: "Das Leben der Anderen" / "the lives of others"

You also can't film / take photo of people in public or put a camera in front of your house if it has view of the public street.

[strogonoff]

Thanks for clarifying. I watched that film (though a long time ago), and I’m familiar with the issue. In my mind, coordinated surveillance by the state or any single entity is highly undesirable, but is a different concern. Surely if one can be held liable for, e.g., using a visible act of filming in an attempt to make someone [physically stronger or better equipped] stop breaking the law, one may end up feeling fairly powerless in a variety of situations.