"The Man" does not exist, although interest groups certainly do, and the Iron Law of Oligarchy always holds, and I'm always willing to entertain conspiracy theories. But my impression is that the highway system was built because folks like Robert Moses and Ike genuinely thought it was the right thing to do. Cities were in fact massively overcrowded, jammed with congestion, and to be able to escape the tenements of New York and to be able to have the complete freedom to go anywhere in the countryside and have a picnic in a state park was an amazing advancement. What evidence do you have that the main driver behind car culture was conspiracy?
I'm pretty sure it's just the complex result of simple evolutionary forces and small benign decisions, and not the result of some malicious intelligent design.