Replace "pay for upkeep" with "maximize profits" and then maybe we are talking about the Real World. Tolls will go up, and only a fraction of the increase (if any) will come back in any form to the 'consumer.' Why? Because they can. And they will (if they went to business school).
All hail neofeudalism!
That's not much different than the state controlled infrastructure. The Dulles Toll Road in Virginia was paid off shortly after construction, now it's just a revenue generator.