Roy S. wrote:

How does it work at fields where locally based aircraft are exempt from landing fees? Do the guys in the tower just recognize the tail numbers of every based aircraft?

Bridgeport doesn't charge landing fees for T&G ops, unlike some
airports. I'm told Farmingdale on Long Island charges $2.50 per ldg
which is why they cross the Sound to go to BDR for practice. Landing
fees are billed every month from the list of IFR arrivals - this list
is compared to the based aircraft list and the local aircraft aren't
sent a bill. VFR arrivals are on the honor system to sign in at the
terminal, and they're sent a bill at month's end. BTW most controllers
do recognize tail numbers of based aircraft after a while.