One of the main reasons that the main toll plaza on the Greenway going west costs so much is that a buck fifty is added for leaving the Dulles Toll Road.
I still remember when, in the mid 90s, they finally added gates to the toll plazas on the Dulles Toll Road. On one side of the toll plaza was a stack of fresh gates. On the other side was a stack of broken gates.
Guessing that a lot people just ran through those toll gates without paying.