They're generally very into enforcing the FCC rules, and calling the feds is one mechanism for doing that.

Here's an ARRL article from 11-2016 (re the shutdown of 11 FCC field stations) which details plans and motivations.

https://www.arrl.org/news/fcc-special-counsel-laura-smith-sa...

In a more recent post (which includes good suggestions for experimenters):

> The ham bands aren’t full of whacked-out haters looking to get rid of everybody else, but hams are very accustomed to people using the bands without a license or not following the band plans, causing interference problems.

https://thesilicongraybeard.blogspot.com/2020/09/a-ham-radio...

Usually the 'self-policing' by hams (it's usually very effective) is done gently. They get that the frequencies are free of $$cost, and don't want to lose (any more of) them.