What is a bunch of random nerds going to do? They have no power to fine or arrest. All they can do is document the evidence and turn it over to the FCC, which does happen on occasion. But, I have listened to ARRL division directors talking about trying for years to get well-documented egregious cases of malicious interference dealt with by the FCC. The FCC just can not be bothered. It's not so much that they can't be bothered to collect evidence, which they can't, but even if they have evidence, that can't be bothered to act on it. The FCC should be a technical organization but is pathetically political.

One of my ham friends deals with the FCC often, because he works in spectrum management at the NTIA. The stories he tells make me never want to set foot in D.C. except to visit all the museums that my taxes fund.

No power to fine or arrest isn't entirely true.

What stops them from finding who's transmitting and then filing a civil suit?

They keep telling you that the FCC has the power to do it but does not have the political will.

You need to get the community organised for a hunt. I recall one that happened when a rogue retransmitter managed to spill religious radio onto TWR2 frequency at local Airport