It's the tragedy of the commons. It's a complete non-issue for the offender because it's very unlikely they will face any consequences and less of a non-issue for their neighbor who suddenly can only receive this guy's Spotify on every channel instead of the public broadcast they wanted to listen (maybe exaggerating a bit, depending on the FM transmitter gizmo used, but maybe now it's all buried in noise when it was clear previously). Even the "size of a wedding reception" can cover several homes in a dense apartment block.

But don't underestimate the stubbornness and time some people can dedicate to complaining to authorities. You might have a neighbor that will send letters about how they have to pay mandatory monthly bills for the national public broadcast they now can't listen to. They will complain and complain enough that eventually the broadcaster will send someone over with a spectrum analyzer and then the ball starts rolling. There have been court cases over stuff like that in this corner of Europe.

But I agree, you can argue those offenders went out of their way to cause trouble. In the cases I read people kept doing stupid things even after several warnings and apparently only got their lesson only when dragged into court.