Having more money lets you buy more of everything. Yet you are only concerned about roads (which aren’t even used by the poorest segment since they can’t afford a car)? Why not focus on making something more fundamental to existence free, like food or shelter?

Oh right it’s because it creates poor incentives and overuse (tragedy of the commons) exactly like we see with roads (and parking). If car drivers had to pay the full cost of the resources they use it would reduce wasteful driving substantially. And we could use money collected in that way to pay for transit (or just give it as a tax rebate to low income people if you prefer).