It's very deep rooted in their culture like cars are here. Today they are probably also very aware of the madness or caos of having their country overwhelmed by cars, so they don't even remotely consider it. It's not just pollution, but the amount of space cars take up could gridlock their already over crowded country. In the USA we have all that space it seems, but most of it is not occupied or is unusable. So the problems exist like in the Eastern highways and the Bay Area where it can take hours just to travel a short distance in a car. You can get there much quicker on a bike or even on foot when bumper to bumper at 2mph takes forever, madness just madness. If you notice on TV, for every 3 or 4 commericals, two are car commericals and the other usually always a drug commerical, plus the odd one out. Very strange country, that land of the free!