size of government and the competence of government

[Jimbean]

Sometimes the government is inefficient but that's likely the best we can get to obtain a "performing" infrastructure without a lot of waste.

How can a process of market tatonnement be efficiently conducted in the case of, say, interstate highways? Companies will build 5 parallel highways and then 3 of them will close down?

You are referring to cases of market failures. Most cases of this can be dealt with by state (providential) or local government.