A more plausible explanation is that there is an emergent phenomenon where the use of cars drastically reduced the degree of coordination required to develop usable residential property. People are generally lazy when they can be, and so future developers took the easy route of developing land without much regard for things like walkability, because they no longer strictly had to. Prior to cars, if a developer did this, they would not have sold the property. Cars dissolved a natural constraint on property development.
Robert Moses was so influential in reshaping the urban fabric of the US to prioritize cars that everything else is basically a footnote.
Not to say that “emergent social dynamics” didn’t play a role, but Moses singlehandedly built most highways in NYC, and influenced hundreds (thousands?) more around the world. And he built them not simply as a response to emerging demand, but because he personally saw cars as the future of transportation.
I suggest reading The Power Broker to learn more about this; I wouldn’t have believed it either before reading it!