I’ve seen the number of induction coils increase drastically over the years in The Netherlands. They are quite easily recognizable, as there’s typically a solar panel on a pole, that appears to provide power to the system.
Considering there’s a wide variety of vehicles on the road, surely each variant must have (slightly) different characteristics when passing over the coil; especially when in a specific place at a specific time.
And given that they are situated at highway exits (see picture) or after entrances, and road users unable to exit and enter elsewhere, it would be trivial to track the bulk of a vehicle’s trip.
This in context of ALPRs (in different forms) being in place at strategical locations (large junctions or at bridges or tunnels, and parking), and the address of vehicle’s owner; you’d be able to connect the dots, and end up with a pretty complete picture.
The gained advantage in your theory lies in drivers being unaware that they’re being “scanned.” They are not doing a great job at hiding this then, are they. A motorcycle could evade this all together, a car might also be able. And the solar panel could better be used to power a camera and/or a license plate reader if they wanted to know who is passing.
I’m sure if we put enough lab coats on the task they can come up with a system that can ID a model by the reaction in the coil. But at what cost? A light switch is cheap. A light switch that can tell who is using it surely isn’t. And why go to this length and not just do the cameras? Ockham’s razor.