I really do NOT understand the point of arguing about our supposedly being in a better position (possibly) if we did NOT have roads. That makes very little sense (even if it were true). Currently we have roads, and that is our starting point.. NOT some hypothetical fantasy land world without roads, and that life without roads may be more of a Richy_T argument rather than attributable to other libertarians.
Again, you miss the point. It is not about the roads directly, it is about government control of the roads. Now, you will say that the government has to be in control of the roads and that, indeed, is the point of contention. That centralized control reduces the opportunity for a wider range of solutions.