Take a walking tour of pretty much any community and you will find that people have no idea anymore about their own neighbors. We are no longer a country of people who gather on a regular basis to compare notes and swap news, everyone is inside watching the tube, or tapping on a keyboard ;)
To a degree that depends upon your job and how much it takes you into contact with your neighborhood. But I think that you’re right to assume that many people have little or no idea of who their neighbors are.
I try to get to know most of my neighbors. It’s always good to have people nearby that you can count on if something comes up. But I’ve had a lot of them move out of the state in recent years because SoCal is no longer comfortable for them.