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!
Why do you think other causes outweigh the well-documented efforts of Harry Anslinger?
I am not personally against marijuana at all, I just like to understand the perspective of people I disagree with.
The war on drugs isn't an abstract topic, and the architects of who promoted and effected it did so out of openly racist and malicious motives which they were recorded as saying. If you actually tried to understand them by listening to them, you'd find that they really were malicious. To truly understand their perspective you'd need to acknowledge when they held malicious and racist perspectives, otherwise you're actually actively working to not understand.
This is different from the ban overall, which is what the GP post was discussing. I don't dispute that sentencing lengths for a crime could be or were determined by specific individuals.
I dispute that the ban broadly can be attributed to this, and that, by implication, the public opinion at the time was caused by some sort of propaganda brainwashing.
Also just want to add that a common trope of anti-minority sentiment is that the majority group believes that the minority group engages in immoral behavior. This does not logically imply that the majority group's belief in the immorality of whatever behavior was caused by anti-minority sentiment.