Lots of reasons for this, but one thing that is rarely talked about is technology. 30 years ago, a telephone was a luxury. 15 years ago, ditto for a mobile. Now we communicate all the time with phones.
You used to have to get on with your neighbours, as if you wanted help, it would pretty much have to be a close neighbour who would help you.
Now, since everyone has a phone, car, computer etc, it is very easy to ignore your neighbours and speak to (or ask for help from) people you know, no matter how far away they are.