One of the oldest criteria of being a real state is the ability to control who enters and leaves your territory. Unrestricted border control is basically givin

One of the oldest criteria of being a real state is the ability to control who enters and leaves your territory. Unrestricted border control is basically giving up nationhood, and that's not done lightly. Imagine if a regiment of armed Russians decided to "travel" into, say, Poland for a "holiday jaunt". That's unacceptable. Similarly, having lots of Americans deciding to move into Canada would be violating their sovereignty. It's really weird that this is something a lot of folks these days have trouble with.