I think the Dutch bike experience is the result of a conscious decision to make cycling feel safe and convenient which was partly motivated by the 1970's fuel crisis.
The real puzzle is why is this the only country make that decision. See also http://www.aviewfromthecyclepath.com/2009/10/effect-of-hills...
Thanks that's an interesting link. I think it backs up what I'm saying though, even with a fantastic cycling infrastructure, hills half the number of trips by bike.