Well it's not 100% true, but Finland and Sweden are somewhat different about this. It is a common joke in Finland, that if someone smiles in the streets, the one smiling is either drunk, crazy or a foreigner.
Finland is not that bad, actually, at least not with the current generation. I once smiled to an older woman (60+) and she stopped and asked "Do we know each other?"
We didn't, but I was surprised by the idea that you can't smile to someone unless you know them.
Right @apsu