How well do you know your next-door neighbors?
There are six apartments and 15 people in my building and, other than myself and my wife, I can not correctly identify who goes with which spouse, child, or apartment. So, uh, not very well.
On the other hand, they all know who I am. Possibly because I am the only non-Japanese for miles around. Or maybe just because they all wish to be my friend, but probably not.