Enforcement action is likely driven by complaints from other users.
Both FM broadcast and telcos pay for their exclusive slices, so enforcement happens quicker.
That's speculation. I know what is written in the notices and orders. The orders do not cite either complaints or determinations about interference. The notices do. Some of these document complaints with the formula: "in response to complaints." Others do not, such as this[1].
My inference is that when actual complaints exist they are documented, for evidentiary reasons. Thus, when the existence of complaints is omitted, no such complaints exist.
It also depends how long your pirate station operates. If you run maybe 30 minutes in irregular intervals and don't bother anyone, no one will care too much and by the time a van comes around to triangulate, you're off the airwaves.
But if you run for hours every day, and you run a shitty PA with a too wide bandpass filter, that jams other stations? Oh boy you'll get v&.
