Advantage pointed out that its fee was fully disclosed on the rental agreement he signed. Mr. Bauman argued that he didn’t notice it among the fine print and that it went otherwise unmentioned.

“There’s no way we would have ever paid a fee like that,” he said.

Adequate disclosure has been the crux of the issue as it has played out in litigation and regulatory actions. And travelers at the head of a line, at a rental desk, on a timetable, can be harried, vulnerable, undiscriminating consumers.

“Often they are not in their home jurisdictions,” said Bruce Greenberg, a lawyer who has represented drivers in two class action suits, “so they are not familiar with how tolling works there.”

The companies say the fees cover things like the cost of maintaining fleets of transponders and coordinating payments with local authorities. Greg Scott, a spokesman for the American Rental Car Association, said its members find “themselves in a challenging position: making sure tolling authorities — who use different transponders, payment and accounting systems — receive the payments they are expecting, while also making sure rental car customers receive disclosure and transparency about those tolls and fines.”

The Dollar Thrifty Automotive Group has prevailed in two suits where judges agreed the fees were appropriately outlined in rental agreements that drivers signed. But last year the company settled a lawsuit brought by the Florida Attorney General by agreeing to put $330,000 toward possible refunds and pledging to provide adequate disclosure about fees and about how drivers can avoid the charges.

Hertz agreed last year to pay $3.65 million to San Francisco to settle a 2017 lawsuit in which the city accused it of deceiving customers about the fees they could face for crossing the Golden Gate Bridge. Hertz acknowledged no wrongdoing. It revised its toll policy nationwide in 2018 and now charges a $5.95 daily fee for use of a transponder, but only on the days when tolls are actually encountered.

Though that policy addressed the criticism, Charles Leocha, the president of Travelers United, an advocacy group, pointed out that Thrifty, which is owned by Hertz, still typically charges higher daily fees for every day of a rental, regardless of whether a toll is encountered. “They are just seeing how far they can go with the different standards,” he said.