I do that too when entering a plane... set if for Protection
My impressions exactly on Amsterdam. It was a very frightening experience to be a female traveling alone, exploring the red district, seeing how the city turns around 18h... From family/ students/ workers time to male tourists looking for sex-drugs and fun. I was a bit disappointed because I expected open-mindedness, a freer society. But, as you said, most Northern Europe Cultures are only free in the mind. No emotional vipassana experience. It was difficult for me.