The rental car companies approach it differently. For example, Hertz offers a plate pass with every rental at no additional cost for the service; they simply bill for the tolls accumulated (I did not check if there was an extra service fee on that one). National charges $2.50/day or $10/week for the automatic toll payment.

BTW, Colorado has gone the same way with their E470 road outside of the Denver airport. No toll collectors.

The rental companies can and should alert renters BEFORE they leave the airport to this situation. It's regrettable they didn't in Dallas.

Cheers, Anne