Even if there is only 1 per 365 square miles (sorry, missed the box car that estimate came off of), not every 365 square miles has one. Density varies with availability of resources. That's how it works with populations of living things.
I suspect there are a lot more of them out there than some people are willing to accept but fewer than other people assume. If you happen to live in one of the more densely populated places AND have interaction, I think you would assume many more other people are having the same experience. On the other hand, if you live in a place there are none, you might reasonably think other places are like where you're at. Lot of people live in places there seem to be plenty of them but are just oblivious.
Something I've noticed ... as time passes, I seem to be picking up on their presence in places I had not noticed it before. Not always, but off and on, so I don't think it is just "bigfootitis". Also, when they do show up in those places, it seems to be more quickly after my arrival if it happens at all. So ... what's up with that? Have I finally polished my awareness enough to notice what has been in front of me all along or have I become tolerated by them over time?
I don't know. Figuring it out gives me something to focus on while I'm out there.
MIB