> There might be plenty of good reasons not to prefer the more efficient public plan, but the fact that it would put toll road vendors out of business isn't one of them.
I have no particular sympathy for any private provider that can't compete with other private providers in the market. However, from my point of view private and public providers aren't in the same market, or even providing the same product: one is simply selling access to roads, or health care, while the other is giving these things away bundled with the dubious "service" of compelling other people to pay the bill. To me that bundled "service" is of immense negative value, and the existence of the public system is driving the providers of the unalloyed product I actually do want out of the market. So, from my point of view, the fact that the public plan would put the toll road vendors out of business and thus leave me with no decent travel options that don't involve externalizing the cost onto others is actually a good reason to oppose the public plan. (There are others: While I don't want to participate in this externalization process as an unwilling beneficiary on moral grounds, I'd also prefer not to become one of its victims.)
Of course, if there exists a way to build and maintain a road at a cost of $1 per 100 miles, there is no particular reason why that cost couldn't be payed through tolls instead of taxes, thus giving us the best of both worlds. There are basically only two ways which public services can manage to cut costs compared to a private provider. One is by externalizing the cost of the service onto non-users, and the other is by being exempt from regulations which private providers would be forced to follow (or, equivalently, having the regulations tailored to suit the public service by sympathetic legislators).
> Capitalists don't mindlessly prefer private things just because they're private.
Whereas libertarians such as myself do prefer private things simply because they're private, which is to say: because they don't involve the use of force. Which is not to say that there aren't practical reasons to prefer private systems as well—just that, to me, any system which involves force is automatically more costly than any voluntary system, which makes these other reasons more-or-less irrelevant.