[mdemare]

Transportation may be a good, but infrastructure isn't, and there are good reasons why depending on the free market to invest in infrastructure is a bad idea. It is very hard (and wasteful) to charge for roads. Infrastructure forms a natural monopoly (worse even than the telecom industry). There are huge sunk costs. The existence of roads benefits everybody, even those who don't use them, but nobody wants to pay for them.

I like free markets too, but whenever there's something like the Tragedy of the Commons or Moral Hazard involved, free markets lose much of their advantages.

[Prrometheus]

I mentioned this in other comments, but private roads, highways, canals, and railroads (even one of the four great transcontinentals) had a long and successful history in the United States before the rise of public monopolies. Since it is clearly possible to build even very expensive infrastructure by private means, we have to ask if it fair or efficient to do otherwise. Is it okay to tax people in California to pay for highway boondoggles in Massachusetts? Is it in society's best interest for infrastructure to be built by entities that have a history of being behind schedule and over budget? Is it wise to build more highways than the free market would provide in order to have cheap transit when all side effects are considered? I'm not sure.