Necessary for the state to get revenue? Yes. Moral? No
It has been my belief that taxation is theft.
Taxation is sort of social contract (yes, I hate Rousseau, but couldn't think of any better word now). Taxes are necessary so the state can protect you.
I've never understood the "taxation is theft" argument. Without taxes nobody except the super rich would be able to actually afford to live. So only people who drive on the road should pay for it? Ok, well have fun with massive tolls that nobody could afford to get anywhere but you know "fake freedom!".
IIRC, are not highways already currently funded using the gas tax?
Supposed to be, but roads are hugely subsidized since it won't cover the cost. In WI it hasn't been raised in forever and there's a massive deficit for roads, they're bonding many millions each year now.