They don't have to "fight" to pay for it, they just need to use tax money to do so. The problem is that voters don't want that. Voters are perfectly happy to massively subsidize infrastructure for cars (those roads aren't free), but they don't want to subsidize public transit, and claim that public transit should somehow survive on its own (even though roads don't).

>as there are no perfect solutions when capitalism is involved.

There's nothing "capitalistic" or "free market" when it comes to the road system in this country. It's purely socialism. Charge use-based tolls for every road driven on and things will change quickly.