alt Hacker NewsEz pass billing is all over the place, each state/authority does whatever it wants.
If you reg a secondary car’s plate to an ezpass account without using the transponder, a lot of states will just think it was a read fail and charge you the regular rate but it depends.
The less honest states (New Jersey, probably others) will charge you a punitive fee (which doubles if you don't pay on time) for not having an EZpass on that vehicle. And then when you call customer support they'll argue with you, until you call on the last day when they finally agree that everything was good and proper.