That is the entire point. Why are we subsidizing other peoples' bad decisions? If you want to go shop for fast fashion every other day or drive a 9,036-pound electric Hummer the rest of us should not pay the price for your jackassery.
Say that all logistics companies switch to the bigger trucks and now only pay half of their costs, so e.g. 3 billion instead of 6 billion per year. Now assume that road maintenance used to cost 1 billion annually. With the new system it will cost 5.33 billion. So you have savings by the logistics companies of 3 billion per year contrasted by additional maintenance expenses of 4.33 billion per year. So your economy now spends 1.33 billion more per annum on transport, if it's through a higher base rate on your car's license or through more income taxes being redirected for road maintenance instead of building schools or whatever.
These numbers are totally made up for me, and were only meant to demonstrate that not internalizing externalities can lead to inefficiencies.
It's true that if you increase taxes for heavy trucks, customers will notice it via grocery store price increases. That's maybe the problem why it's not being done, because voters notice it way less that a road repair is more expensive and thus a school can't be renovated or something.
But the market can't optimize for a cost it doesn't know about. If you're just funding road construction and maintenance with income taxes and people aren't paying those costs in proportion to usage, then there's zero reason for the market to do anything to try to reduce those costs.
It sure is convenient that it's "not productive" to debate one of the biggest and most obvious downsides to what you're advocating for.
Don't get me wrong, I loathe the people who have a 4Runner for a household with one kid but their stupidity might just be collateral damage of an otherwise decent overall system.
Such a tax should be as close to an approximation of the actual cost of road maintenance, full stop. If it makes certain vehicles uneconomical that's the intended effect.
Of course you'd want to grandfather in such a drastic policy change, or phase it in at some % per year.
1. Taxing this based on axle weight is also stupid. In reality road wear is a function of tire width/shape/size etc., speed and numerous other factors.
