Gianandrea Heyer :Public transportation in the US

I was reflecting about how the US could make a step toward a greener future, helping the environment to be cleaner. I noticed that in the US the public transportation is very weak compared to European countries and I started thinking about it. I noticed that the distances are way bigger than the ones in Europe because Virginia is twice as big as Switzerland for instance, which makes it harder to cover the territory with a good public transportation net. But then I also thought that the mentality here is different and people like to use their car instead of buses or trains. Why do you guys think this happens?