Sigh. I see again why I stayed in Norway after my "year" abroad, nearly 38 years ago. In not insignificant part it was to escape the anxieties of the US. Here, we would answer the door. We might peek out the kitchen window first, or keep the door on the chain, but we would definitely respond. Not that all is good and happy when we answer the door after midnight. Once it was DH's niece, come with the message that his father had just died. And sometimes it's been some drunken kid asking "is this where the party is?" But it's never been dangerous. Not so far. So to me, the US approach seems paranoid, but also maybe paranoid for a reason.