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.
A team of professional engineers couldn’t detect terahertz radiation without grown nano scale antennas any more than they could use the coils of the size implied in your picture to differentiate between two cars of the same make and model let alone cars that aren’t in wildly different weight classes.
It’s not a question of pointing enough clever people or computing power at the problem, it’s a question of trying to dig a hole with a ball peen hammer in one swing. The tool is inadequate for the job, uses the wrong motion and doesn’t have enough time to do anything.
and for the example you gave where analysis isn’t definitive but could be paired with automated readers to clarify a picture, simple presence detection does the same thing and costs much less!
And come on, you know that just to cut those little octagons in the asphalt, drop in the coils and tar over em they’d send a ten man crew in four diesel trucks and shut the ramp down for the whole business day.
I've found a video that clearly demonstrates the concept I have in mind, just to make sure we're on the same page; because I'm not sure we are. If simple presence detections, even in the context of many vehicles in close proximity of another, and changing order through vehicles overtaking others, then I would agree; but that's something I find hard to believe. I can't really argue with the last point though, because it should be considered universal truth...