Mz
You assume that in the prevailing tax structure the roads and bridges could not have been maintained. That is not necessarily true at all. Logically we can see these are independent policies.

We could easily have built less new roads and maintained the old. Or changed the tax structure and still failed to maintain the roads and bridges.

Generally the states & localities maintain the roads even if built by the Feds. The taxes you refer to are federally set by the congress.

You have built a bridge too far here.