Extraordinary claims require proof from the party making the claim. How do libertarian and/or anarchist propose that intercontinental freeways be built and maintained at the same cost as they are done by the US government?
I suspect one reason for that is that their primary competitor is government, which often has major advantages, like the legal authority to seize property right right of ways and virtually endless funds through taxation and debt.
I don't think that any proposals would claim that all things created by government would exist in a stateless society. Remember, it's possible to not have things like intercontinental freeways but to instead have more economically efficient solutions. The road system in the US, for example, isn't some example of "pure economic good." Freeways require people in cities to subsidize people in rural areas. They also are a massive subsidy to the automobile industry, and a disaster for the rail industry. It's conceivable that a much different (and more efficient) organization of society could emerge without the government creating what it judges to be the "best" public works.
The interstate do not arise in vacuum, nor are they product of mere transportation concerns. They are product of very reasonable concern of quickly transporting war equipment and connecting parts of countries to one another, so as to facilitate quick movement of goods and people, adding their value to GDP. The rail industry is thriving well, doing its job as low cost goods carrier.
"It's conceivable" -- except no one has given good argument that thing which is so obvious has escaped human imagination for close to 10,000 years now, and all the places which are good approximation of said ideologies have people in utterly poor state.
Pardon the snarkiness, but did you learn that in public school? I ask, because I had those ideas unabashedly hammered into my brain my entire childhood in government schools. The problem is that whether someone consents to the actions of government empirically does not matter. Even the founding fathers either deliberately perpetuated this clever lie or managed to deceive themselves like a lot of Enlightenment philosophers. "The consent of the governed" and so on.
For sake of simplicity, lets talk about UK. If the consent of governed does not matter, why hasn't David Cameron taken all the land for himself, a la William the conquer? Was the history of past 1000 year just sham? Something people told themselves to drink the cool-aid? Did all the workers who rioted and all the people who fought and died on side of Parliament against the King stupid? Why exactly are these people living under lie? And how does that country, based on lies and shams, has a well functioning society where you can go from being born in poverty to governing the country in one life time?
And any ways, you still haven't answered the question. Why aren't there incredible large scale projects popping up in north Mali, where Caterpillar industry can go tomorrow and built awesome infrastructure? Surely we in democratic world have to face the tyranny of government in every step ... why haven't the more enlightened countries with little government shown us the way? And if everyone can be lied and manipulated, how is this perfect utopia of anarchy supposed to work?