Until the development of electronic transponders, there was a physical limit to how quickly you can collect tolls. It may be somewhat practical now that you have drive-through tollbooths, but there are a bunch of other problems it creates. For example:

Roads are a high-fixed-cost-low-variable-cost industry. I posted on these at Reddit - http://reddit.com/info/2fquz/comments/c2fttk. Everything that's wrong with airlines will go wrong with roads, and more. I suspect that you'll see massive overinvestment in roads as road companies try to capture market share, then the huge number of intersections (all toll, remember?) will reduce driving efficiency.

Free markets solve a lot of things, but they don't solve everything. There's no magic wand that makes them more efficient than a public solution. There are, however, a series of incentives and information-transmission mechanisms that usually give a free-market operator an information advantage over a public operator, hence letting them produce more efficiently. If the incentives point in the wrong direction, though, you get less efficient production.

You seem to be asserting that consumers are not better off with the airlines deregulated. Although I hate air travel and everyone likes to complain about it, I don't think you can argue that, as government has been removed from airline regulation, air travel has become vastly more cheaper and available to more people and that it is possible to reach many more locations by plane.

Similarly for another high fixed cost industry which you cite - telecommunications.

Free markets might not solve everything, but they're almost always better than the alternatives. As examples of the alternatives, consider the postal service, government-run schools, Medicare and welfare.

The governments subsidize airports through enormous amounts of land close to cities at below market rates. Without this intervention, airfare would be much more expensive. Do you think we would be better off if airports would have had to purchase their land on a true free market or is it good for a government to give airports cheap land?

It's hard to know. Presumably the system would look different today if the government had not distorted it in that way. Perhaps if market incentives were allowed to operate instead of the land being taken, we would all be flying around in the jet cars we expected.

I doubt it. Fossil fuel based flying cars are even more unsustainable than our current cars...

You sound so sure. You don't think if the enormous amounts of subsidies the government had spent on airports had instead been allowed to flow to alternative transportation modes or energy research, things might be different?

OK, it is certainly true that things would be different in a better way if our government would spend a sizable portion of the taxbase on energy research instead of wasting it an utterly insane manner.