Tamago is right.
Apple only choose those countries with potential markets and make
iTunes Music Store available to them. Its for people who wants to
support singers by buying legal musics, yet did not want to buy the
entire album because they only like some songs.
As for why you cannot even find what your are looking for in iTunes
Music Store, its because when not logged in, you can only see some
items. The full list will only be available when you log in.
