The FCC does hunt down illegal AM/FM broadcast transmitters in residences. They publish several forfeiture orders every month for pirate radio stations (often in residences,) whether their interfering or not. Hunting these is lucrative business given the PIRATE Act (S.1228) and its hefty fines.
I've never seen this happen for a WiFi band operator, so yeah, they're aren't looking. They certainly could though: someone is using all those grey market boosters. Some of those have enough power to show up for many miles, and triangulating them is quite easy.
They do go after cell jammers. One example from 2016 was a guy in Florida using one in his car during his daily commute. People complained their signals failed at about the same time every day and the FCC pursued it and caught him. $48K fine.
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 The orders do not cite either complaints or determinations about interference.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&.
I've never seen this happen for a WiFi band operator, so yeah, they're aren't looking. They certainly could though: someone is using all those grey market boosters. Some of those have enough power to show up for many miles, and triangulating them is quite easy.
They do go after cell jammers. One example from 2016 was a guy in Florida using one in his car during his daily commute. People complained their signals failed at about the same time every day and the FCC pursued it and caught him. $48K fine.