But in a cost cutting move they handed over most of the monitoring of the ham bands over to volunteers organized by the ARRL. Testing was also turned over to volunteers and you no longer had to go to the local FCC offices.
As a result the FCC personnel lost contact with hams. This in my mind is the only reason that this letter could have been sent. If they have proof that these communications are taking place they should say so. Hams do a lot of volunteer work in their communities and it's like the federal government all of a sudden feels they are untrustworthy. This did not sit well at all with the hams I know in our local community.
CB'ers used to buy ham radio amplifiers and use them illegally. The ham band of 10 meters was close enough to the CB 11 meter band it could be done with little change.
So manufacturers at the behest of the FCC started removing 10 meters from linear amplifiers. If you showed proof of licensing you could get a plugin to add back the 10 meter band.
In the Capitol area, it's highly likely multiple agencies are capturing all RF for later analysis. This is also not used for FCC rule enforcement.
The FCC has the ability to locate signals using directionfinding equipment, but as mentioned elsewhere, usually that's left to Amateurs themselves on their bands.