It is not only the US that is like that. Also in Norway it is considered a secret, and you can get a worrying amount of information about someone just by having

It is not only the US that is like that. Also in Norway it is considered a secret, and you can get a worrying amount of information about someone just by having their social security number. My guess that this is misguided and muddled security thinking behind this, and is something that happens when the involved institutions do not have a coherent understanding of information security.