Unfortunately, this difference is less than it seems. As I pointed up up-thread (using a computer example, no less!) the line between capital good and consumption good is blurry. The exact same object can fulfill both roles depending upon use. Furthermore, one could just as easily conceive of a situation where access to consumption goods was entirely dependent on others and would cause deprivation for those unable to afford the requisite goods. Yet, personal property is universally recognized. The crucial distinction is not the ends to which the goods are to be employed, but the means by which they are acquired.
The reason land and capital ownership arose late is because until there was an economic need for such forms of ownership, asserting such ownership required a person to be extremely mean. Even when the need arose, the actual development of such property systems frequently involved force and brutality rather than a peaceful transition. Ultimately, though, I come to a similar conclusion, that many property titles are of dubious origin and that revoking them is not necessarily "theft." The proper solution in many cases is to treat such property as unowned and then have it be homesteaded by its current users (i.e. feudal land to the peasants, state owned or subsidized capital to the workers).
The actual difference is that libertarians factor in deterrence. The goal of military defense is to make invasion appear unprofitable, not to stop an invasion cold. A militia system can do this quite well. See, for example, Switzerland during WWII.
Thinking about it more, though, you might be right about the South. The willingness of average Southerners to fight a guerrilla war in defense of the privileges of their elite was probably limited and perhaps the lack of ready-made nationalistic institutions would have made for a shorter and less bloody conflict, and potentially no conflict at all.
I'm certainly not saying that such transport isn't desirable, or that people shouldn't be able to build means for easy travel or even that they wouldn't have done so absent the subsidies. However, the cost isn't properly distributed to the real users. Highway deterioration is almost exclusively caused by large trucks, yet, gas tax revenue from small vehicles are considerably higher than their percentage of the costs of road maintenance. If we actually charged heavy vehicles a road use fee proportional to their effect on road upkeep, it would break up the big national retail chains in short order. Your family car trip to the Grand Canyon, however, would proceed without incident.