California, and I think other states, are studying this as well.
It took me a while, but I think I figured out what this is all about.
First of all, let's dispense with the absurd claim that the problem is people buying more fuel-efficient vehicles, thus reducing fuel tax revenues. Cars that get better fuel economy weigh less, and thus result in less wear and tear on the roads. Plus, they could simply raise the fuel tax if there isn't enough coming in. It must be something else, then.
They are afraid of the impact of alternative fuels, especially those which can be produced at home.
There are a number of people here running biodiesel and waste vegetable oil, many of whom are probably not paying road tax. If an idea like that catches on, even if most people can't be bothered with the hassle, it sends a message that this tax can be evaded, and the state can't stand for that.
What is to prevent people from removing/disabling such a device or someone detecting it has been? Nothing.
Even the advocates of such technology have no clue as to how it works or how easily it can be hacked or infected with a virus...