Road wear is disproportionately caused by heavy vehicles; one study estimated that "one 18-wheeler is equivalent to the impact of 9,600 cars". The gas tax is primarily a subsidy designed to support the trucking industry.
Or you can think of the trucking industry as subsidised. Trucks are used to haul goods to shops yes? Taxing them more will just increase the price of everyday goods and services (that depend on goods to function), it will unpopular among just about everyone but the rich (who won’t feel the impact of the price increase much).
You're not wrong, but this is the part where capitalism is supposed to encourage people to use methods that cost less in externalities. Businesses should pay for their externalities or else they aren't competing with each other fairly.
The question of who it is a subsidy to is important, but it is better to directly give them a subsidy than to skew the upstream market towards vehicles that damage roads and cost a ton of money to repair.
I doubt we'll get there though, I admit that we can't get anything effective done. And we'd need to effectively keep prices from rising at the register to even the playing field for infrastructure expenses.
There is nothing we need but food and shelter, which is not the main payload for those trucks.
While some people might enjoy some of the useless consumerism crap that's moved from China to your closest shopping center via trucks, I enjoy driving my old petrol car through the landscape and to the track.
Now let's all step back, calm down and compromise. :)
