I'm old enough to remember when you knew everyone in your street or neighbourhood. The same cannot be said nowadays, and therein lies part of the problem. How many of us can claim today to know most of their neighbours? There are even people living next door to one another who don't know each others names let alone anything else.
It's a sad indictment of today's society that too many are caught up in their own busy lives and schedules that they are totally unaware of what's going on through the wall.
I'm far from being a "nosey neighbour" but I happen to know all my immediate neighbours by their first names, and their children too. I don't go out of my way to do so, I just make the effort to chat when I see them. That may sound odd, but how many of us merely nod to one another without actually knowing what kind of person it is we're nodding to? Some people actually seem to be intimidated by this fear of familiarity with other human beings.
Thankfully I have wonderful neighbours with lovely kids, however if I knew that something dreadful was going on I know that I would inform the relevant authorities, especially if it were a child involved.