another story that readers should be alert to: You only have to pay one way if you are passing through tollbooth at the entrance to the airport.
If you are driving into the airport for pickup/dropoff, save your toll receipt when you go in, and on your way out, flash it to the toll booth operators in lieu of payment.
Apparently, the toll takers will not let you in on this little secret if you offer to pay and will collect your toll anyhow.
A scandal broke out a few weeks ago when this was discovered.