Answer me this. If they had not built roads and bridges for the increased number of poeple back then, what whould they have done for work? How would they have sold their cars? What type of manufacturing could they do or agricultural activity to support themselves. Increaed productivity put them to work. In fact the only way to justify the interstate highway system was defense. The money spent could not justify be justified by transporting goods. In fact railroads are far more efficieint (energy, safety, etc) than roads. There are many thoughts on why and who got roads built. The simple fact is in many ways it has cost us dearly.
The highway system lead the car sector and not the other way around.
