Sure, but the interstate highway system's capital costs are paid mostly by the federal government too -- gas taxes don't come close to covering it so it's decid

Sure, but the interstate highway system's capital costs are paid mostly by the federal government too -- gas taxes don't come close to covering it so it's decidedly not user-pays -- and nobody expects that to be profitable. National transportation infrastructure is a public good, not a business investment on the part of the government.