I would make the opposite argument actually. Car drivers pay the same amount of taxes despite taking up more space on the road, causing more accidents etc. It's an unfair subsidy loophole that is finally getting plugged.
Buses, on the other hand, are a loss-leading and highly subsidized form of transport.
Your statement is absurd. You're arguing that something should have the right to occupy the public space and deprive others from using it just because the owner bought it and spends money on fuel.
Fuel taxes, sales taxes, and usage fees (tolls) generate roughly $150 billion per year.
Excise taxes do not even have a good national accounting system and I can’t find a US total number. But, for example, just CA generates roughly $10 billion in revenue from these fees.
Far from not covering the costs, the direct taxes and fees on cars are actually generating a profit.
If you want to talk about externalities you have to account for both positive and negative externalities.
[1] - https://www.urban.org/policy-centers/cross-center-initiative...
[1] https://en.wikipedia.org/wiki/Externalities_of_automobiles Extremely conservative list on Wikipedia. Anyone that e.g. has looked at real-estate pricing before and after a street was made car free and has seen valuations go up by x2-x5 can attest even just the impact on direct livability.
Driving carries risk and at scale that risk will 100% every time manifest as real harm. It’s not about whether the risk is there but whether the gain is worth it. A less politically charged example, ordering your steak rare. There is real risk, and people get sick, a smaller subset get really sick. And yet we do it constantly.