One could pretty easily argue that everyone benefits from public roads even if they don't have a car. Nearly all the food and other supplies they use are transported over them.
The gas tax isn't a very accurate indicator of the roads required maintenance costs relative to the vehicle the gas is going into.
I'm not very fond of a mileage tax. It gives incentives to hack the odometer to cheat the tax man. It also doesn't discriminate on where those miles were driven. How much on private property, how much in another state or tax district. It will lead to GPS tracking of all cars so that the car is taxed "properly" no matter where it goes... And with that any privacy on your movements. And then insurance companies will demand access to the data so that people who drive fast, go to higher risk areas, etc. can be billed accordingly... The law of unexpected consequences...
