In a perfect world, the electronic tolling infrastructure in the United States would be Mastercard seamless: Any transponder would get you through any toll plaza, debiting your account as you breeze across bridges and through tunnels with interstate abandon. But you can't. You should be able to though: In 2012 Congress passed a law requiring the nation's various electronic tolling authorities to come together and make their systems interoperable by October 2016. Should be easy, right? Transponders are simple radio devices. Pop them all on the same frequency, job done.

But, just like they foul up regional transportation systems (why oh why does the San Francisco Bay Area have dozens of transportation agencies?), back-office bureaucratics—specifically the rules that make sure agencies get paid—intervene. The result is a patchwork of regional linkages and a harsh truth: The result is a patchwork of regional linkages, and a half-dozen states running solo, running a year and counting behind on their goal of sea-to-shining-sea interoperability. Except for the most avid road-trippers, this is not an actual problem. But digging into the reasons for this shortcoming turns up the sort of Byzantine rules and internecine squabbling that is all to often guilty of hobbling American transportation infrastructure.

You Shall E-ZPass

The idea of electronic tolling dates back to the 1950s, when Canadian economist William Vickrey imagined vehicles with integrated transponders cruising through sensor-studded cities. Norway put the first real-world system into operation in 1987. “Toll operators thought, 'Hey, this is something that will cut down on labor costs and also be a convenience to our customers who don't want to carry cash everywhere,'” says Patrick Jones, executive director and CEO of the International Bridge, Tunnel, and Turnpike Association. The Dallas North Texas Tollway installed the first US electronic system in 1989. Early on, it and those that followed emulated stop-and-go cash collection: You'd pull up, halt, and an electronic reader would scan your tag.

Those soon evolved into the roll-through systems common today, easing congestion, cleaning the air (fewer cars spending less time idling), and leading to a sharp decline in toll plaza accidents.

Drivers no longer needed to stop and pay with cash but instead faced the prospect of stuffing their glove compartments full of transponders, each one keyed to pay the owner of whichever bridge, tunnel, or turnpike traversed on the regular. In 1993, the metropolitan region encompassing eastern Pennsylvania through New Jersey to New York City included roads and bridges operated by seven transit agencies. For regular commuters, that could have meant keeping track of seven chunks of plastic. Those agencies averted that nightmare by coming up with E-ZPass. Today that system connects bridges, tunnels, and roads run by 38 agencies in 16 states. For drivers traveling from Maine to Virginia, New York to Kentucky, the experience is seamless.

The business deal worked out by that collective to make sure every participating agency got paid for every trip through their toll plazas, is a bit more complicated though. Say you bought your E-ZPass transponder through the Pennsylvania Turnpike Commission, then drive over the George Washington Bridge into Manhattan, then take the Queens-Midtown Tunnel to check out Long Island City. As you pass through each toll, your E-ZPass sends out a code telling the plaza's sensor where you came from. The agency that owns that toll plaza (the Port Authority of New York and New Jersey for the bridge, New York's MTA for the tunnel) sends the Pennsylvania Turnpike Commission a bill for your trip. The Pennsylvania Turnpike Commission pays that agency and deducts the corresponding amount from your balance. An interoperability agreement always pays its debts.