The stretch I dread is not the mountain pass. It is the last forty minutes before the toll plaza on a holiday Friday, when four lanes braid into a slow rope and the car in front of you rides its brake lights like a metronome. I have sat in that rope with a coffee going cold in the holder, watching the electronic lanes on the far left move at a steady thirty while the cash lanes shuffled forward a car length every ninety seconds.
That gap is the whole argument. A cash booth needs a human transaction, and a human transaction needs a full stop, a window down, a hand exchange, and an acceleration back to speed. Multiply that by a few thousand vehicles an hour and the queue is not a mystery, it is arithmetic. Electronic collection removes the stop entirely. The vehicle passes a gantry, a short range radio handshake happens somewhere between the windshield and the overhead antenna, and the account settles later.
I resisted for longer than I should have. My reasoning was that I only took the highway a few times a month, so why bother with a device and a balance to top up. Then I drove nine hundred kilometers over a long weekend and passed through eleven collection points. Eleven stops, eleven decelerations, eleven merges back into traffic that had already closed the gap behind me.
The part nobody mentions until it goes wrong
Transponders are not interchangeable, and the failure modes are quiet. A unit mounted too low reads inconsistently. A windshield with a metallic coating can attenuate the signal enough that some gantries register a pass and others do not. Battery powered units die without announcing it, and you find out at a barrier that does not lift. Cigarette lighter powered units draw from the car, which is fine until you swap vehicles.
Then there is the balance question. Prepaid card slots, linked accounts, auto recharge from a bank. Each has a different failure story. Auto recharge is convenient right up until the linked card expires and you are the person holding up a lane you specifically chose to avoid holding up.
Korea is an odd but useful place to look for comparisons, because the Hi-Pass system has been near universal there for years and the terminal market never consolidated into a single vendor. Drivers buy the hardware themselves rather than receiving it from the toll operator, so the arguments run at the level of the individual unit: whether a built in battery beats a wired one for someone who alternates between two cars, whether an adhesive mount survives a summer dashboard, how a card slot behaves differently from a linked account when the balance empties halfway through a trip. Those model by model differences get covered in more depth here, which is what happens when the device is a purchase and not a rental.
One idea out of that stuck. A transponder is not a toll accessory. It is a piece of the car with a service life, and it fails the way car parts fail, quietly.
Now I check the balance the night before a long drive, the same way I check tire pressure. It takes about eleven seconds. The last three trips, I have not seen the inside of a toll booth.