At this point, they didn't want to let EVs off the taxation hook but setting up a bureaucracy to collect EV mileage based taxes right now would cost far more than it would collect. The whole EV tax thing is mostly symbolic as the revenue is pretty minimal and will be for some time to come.
The fairest tax would be based on the product of miles driven in washington state and the weight of the car or some other measure of impact. Of course no one would stand for government gps tracking. Except we already have that with our phones, thanks NSA
Maybe we can get to a system where we just report our mileage once a year or something, and pay based on how much you drive that year. Yes, we drive out of state and so we'd be paying "extra" for that. For the gentleman with multiple vehicles, maybe you pay your $150 * number of drivers in your house?
But I don't see a better alternative to some basic tax. Another terrible solution is paying taxes based on how much electricity you use for your car, but evs have different efficiencies. EV owners are an easy mark, because we bought an expensive item and thus don't get much sympathy (unless you are big donors) and are mostly progressives (don't hate me too much), and willing to pay taxes for things that are for a public good. When these incentives were figured out a few years ago, people didn't foresee the rise of luxury evs. You can see that in Norway's probably over-incentive to buy a tesla.
I wonder what happened to the wa states electric vehicle pac deal? I'll have to read the forum and get up to date on that.