Taxing people for the shared usage of infrastructure such as roadways is a reasonable thing to do. Charging people per mile seems like a way for it to get quickly out of hand and a monitoring scheme to track and locate vehicles. Do we really trust the government not to abuse a system like this? A better way to fund infrastructure would be to do it by proxy instead of through direct usage. Because in all scenarios unless used roads cost more than more heavily used roads.

Even if you're charging per mile driven. If you live out in the country maybe only two cars a day ever go down your road. The taxes collected from Miles driven on it far exceed the taxes required to maintain it. So why even do a system like this unless your ultimate goal is tracking the location of every vehicle. Forget that idea that there is a general consensus that we can move from place to place on the public thoroughfares unimpeded. This is Illinois where you're required to get a card in order to exercise free speech, oh wait no I mean you're required to get a card in order to exercise your second amendment rights. Because in Illinois they're not rights they are privileges in which you must beg the government of Illinois to exercise.

A better overall solution would be to levy the tax on businesses. This doesn't reduce the overall tax burden that the consumer has to pay. We all know businesses simply pass their costs along to others. Putting the tax at the business layer prevents the onerous misuse of trying to track everyone's miles driven in order to tax them properly.

A self-driving car may decide to drive around an empty street in a city instead of find parking, because it's cheaper, but its a negative externality.