> Some of the money is used to fund the maintenance of highways, though.
Only in the sense that some of all tax money is used in that way - VED just gets pooled with all tax income, none of it is 'ring fenced' for any specific purpose. That's why the idea of 'road tax' is so annoying, since it implies it's to be used for a specific purpose.
"Road tax" is a _tax_ you have to pay in order to use the _road_. It's the most natural name for it, which is why people call it that.
Despite the words they use, it's not a vehicle tax: you can own a vehicle without paying it as long as you declare that you will not use the vehicle _on_the_road_ (a.k.a., make a Statutory Off Road Notification). It's a tax for using the roads. A road tax.
That the government don't ring-fence it to use on road maintenance is irrelevant.
Only in the sense that some of all tax money is used in that way - VED just gets pooled with all tax income, none of it is 'ring fenced' for any specific purpose. That's why the idea of 'road tax' is so annoying, since it implies it's to be used for a specific purpose.