I will preface that I agree that EVs should not get a free ride, and just about everyone will come up with a complaint on how calculations should be/are being made to pay for roads, construction, and maintenance. If it were to be per kWh, if you charge your car and it sits for a while, you'd be paying for electricity you never actually used, etc.
NH just started a yearly EV fee ($100 for EV, $50 for Hybrid) plus regular registration. I'm curious how this will play out for them. With all the hype of how much more expensive EVs/Hybrids are than ICE (mind you, they can also be much heavier), I think it is odd that it's a flat tax, whereas for ICE it's ($0.222 per gallon). If I were driving a 30 mpg vehicle, this would be about 450 gallons of gas in a year or a total of about 13,514 miles. For some of the target people they WANT to buy EVs (city, commuters, lower mileage folks), they may be the ones paying extra, and not just for the car.
For me, with about 28K miles in my first year (cuz it's so fun to drive and it's a minimum of 20 miles roundtrip just to the grocery), if I were to calculate my GT at 30 mpg, I would have paid about $207 as a "gas tax" for that year. NH is not exactly anywhere in the top 45 states that make public charging available for people who cannot charge at home either.