A) Nothing really applys in USAC unless it's a "real" race - probably because there just aren't enough officials and resources or reasons to utilize all of the UCI type rules. They have built in a lot of good rule building in the manual that leave regulation of the sport up to other govenring bodies and only in events that really "count".
B) As alluded to in A - they don't have the physical numbers to enforce anything that can't be tipped off to by eye at the starter's house anyway. I saw some shady ****ake mushrooms at the TT I rode today.
Saw a Softride beam style frame in a USAC TT event. WTF??!! Damn tri-guys.
...and then they were all running aftwerwards too like the TT wasn't enough of a workout for them...