A team of drivers in one vehicle can make the same trip in about two days. If efficiency alone is your goal, then perhaps the modern road system is a short lived achievement. But to say that is somehow a marvel is misplaced. It moves people away from interaction and pushes them to live farther and farther out. This causes an artificial demand and thus cheaper prices.
Roads are one example.
So too are houses. Either one of which are put to shame by those built in the founding era. Just a thought. So I think that the founding fathers would have gone through with it. What I think you'd hear them say is to ask why we have such unfettered businesses.