Agreed. We don't buy enough bikes. I have a younger cousin who doesn't even drive. He has no interest in it at all. Public transportation is all he takes. In fact, other than sticking his face in his iPhone, he has no interest in anything
My guess is that in Europe they face much denser geographies and populations. In contrast, for most of the US, things are more wide open and spread apart. But the number one reason they purchase more bikes is probably gas prices. They are a lot higher in the EU than here.
Something thing that would be interesting to know, is what size are the bike registrations in the EU compared to the US? I'd bet there are a TON of scooters being registered, which makes sense for the reasons I stated.