Ok this has been bugging me for a while so I have had a good look to try to figure it out and I think I now understand.

Suppose a user is following 'Nottingham North' area.

Another user removes a pub from Nottingham North and it is automatically approved. The system will then look at generating an email notification. Which will go to anyone following that pub, Nottingham town as a whole or any specific areas that it is in.

However as it is no longer in Nottingham North that would not generate any notification for someone following that area.

Does that make any sense?