How would they have realtime monitoring unless they have a receiver in every city in the country? This happened in Jasper Alabama, not Los Angeles California.
I think its possible that they only send someone out once a year to check for active frequencies. When they see a problem (AM 1259 is missing) then they send out the brush crew.
Point being, I highly doubt that realtime monitoring exists everywhere. The owner of this station probably banked on the fact that no one's watching Jasper Alabama that closely. When someone at the FCC gets their annual paperwork about this station, they probably just do a cursory check on it and push it through, not putting a lot of time or energy into this tiny station.
One thing we need to realize, that as computing types, we think of monitoring differently.
Monitoring need not be real time. A yearly inspection can be done. Quarterly. Audits.
Even grocery stores don't get daily or even weekly health inpections.