Why shouldn't the vehicles which do the most damage pay the most tax?

It seems like the point isn't that it's intended to tax EVs, it's intended to shift the cost of road maintenance onto the vehicles that cause most of the road maintenance needs. Basically, it's aligning incentives so that firms bear the true cost of their actions.

If that results in taxing semi and heavy duty trucks, that may be a good thing. A lot of the wear & tear on highways comes from trucking; if it shifts a lot of that truck traffic to rail, it likely would significantly reduce the total cost to society.

It's not flawed logic though. If, say, a mile of highway costs $1 million and it needs some expensive repaving/reconstruction every 20 years, who should bear the cost?

The current model is roughly that all of society shoulders the cost roughly equally per person, regardless of how much they use that road or how much they drive in general. But clearly, some people derive more benefit from the road than others. The guy who doesn't drive derives 0 units of benefit. The gal who drives on it once a year derives 1 unit of benefit. The daily commuter gets 100 units of benefit. For the trucker moving $10M of goods a year on that road, their company gets 3000 units of benefit. So in a sense, the people who drive less are subsidizing the people who drive more - kind of like going to a fixed-price buffet dinner (people who eat more are subsidized by people who eat less).

Targeting more of the cost burden on heavy goods vehicles isn't an issue in my opinion. The thing is, that highway costs $1M no matter what. The only thing we can decide as a society is how to split that cost among the people. In the current way, I think the truck is underpriced and is doing more than its fair share of damage. If we change the prices so that car drivers pay less (not zero) and the truck driver pays more, that's okay. The truck's costs get passed onto consumer, such that people who buy more goods pay more road tax - exactly as intended.

Taking a step back, I think a lot of (not all) problems in society are a result of mispricing - often for political, special-interest, and/or "feel-good" reasons. When people pay less than the true cost, they over-consume. When people pay more than the true cost, they under-consume.