On Sun, 20 Nov 2016 09:13:36 -0700, Charles Bishop
wrote:

As you say, you missed the deadline for using phone or internet and had
to rely on the rental company, which looks to have not charged a fine,
but only a "rental" of the transponder, which looks to be cheap.

My bet is the state has an arrangement with the rental car companies.
If they get a transponder rental fee every time someone passes a toll
booth, it is not a bad deal for the state. My bet is it is just one
computer talking to another so labor is not a big deal.