why media focus on narrower audiences?

Question

why media focus only on specific people and not on the whole nation

Answer 1

The whole nation does not change much in a day. There are things happening to people and things in a nation always. Whichever section gets the limelight is news while some deserving cases do miss the popularity. But do you have the time or ability to be updated about each and every citizen every second?
Nanotechnology days now - everyone knows the mechanism is much deep within the atom. By showing small segments (or narrow segments if you like) the News attempts to characterise a nation.

Answer 2

could you elaborate on your question i.e. some examples.