Here is a link to enforcement actions against unlicensed operators
In the past 12 months nationwide total of 22 cases.
All enforcements were for FM broadcast band
All were warned to stop before they received any punishment
They seem to be focused on pirates trying to compete with commercial broadcast
The rules are there to keep you out of trouble and to give them some kind of basis for nailing the real pirates. If your antenna is 1 foot too long or your transmit power is 25 milliwatts too high nobody really cares unless you cause a problem and then don't fix it.
Even if they find you in violation they will give you a warning before they fine you.