Comment by DiogenesKynikos

Germany is highly federal. The federal government only covers a portion of the cost of road construction and maintenance, with state and local governments carrying much (a majority, I think) of costs.

From what I see in your 2nd link, motor taxes do not even cover the federal government's contribution to road construction and maintenance, not to even mention what state and local governments pay.

You're saying the US doesn't have to subsidize roads, but removing that subsidy would require the US to raise fuel taxes and tolls by 200%. Rail can also break even if prices are increased. The reason governments subsidize HSR is because it has positive externalities.