As far as the "single factor" analysis is concerned, I did not say you were guilty of it, but that is a very frequent argument. Right-wingers blame the perceived failures of the Soviet system on a single factor of their ideological choice - "socialism" while left-wingers exonerate them by pointing to a single factor of their ideological choice - 'US imperialism'.
I fully agree that using buses, bicycles or trains whenever possible is a much better solution than using cars. But my understanding is that car ownership is a big part of macho identity which is alive and well in Cuba. In the current situation that macho identity rides on pollution-generating US 1950s and Soviet 1970s technology. And that is hardly a model to follow.
Wojtek