Difference between Samsung/Apple And rest

This post is regarding Samsung's dominance Vs other OEMs as well as taking Apple into consideration.

Samsung/Apple launch their devices in almost every country And also have good service centers/Stores along with marketing which increases awareness in people whereas other Manufacturers/Companies don't.I have to say Nokia is little exception here as well.

See Nexus 4 or Nexus 10 , Nobody [No average consumer] knows about that device(s) except Europe and US people [Again , only few people know compared to people who are aware about iPhone/Galaxy phone/iPad]

I don't know why companies do this............If they want to sell more, then more people should know about it.

I am from India .As an example , In my country , Apart from Samsung Windows Tablet , no other company launched Windows tablet much widely up here , not even MS Surface.No Nexus available , No Motorola availability.No Xperia T (Only S and SL are available and nobody knows when Z comes) , No Asus tablet etc.

Most people choose only Samsung/Apple/Sony , Most people chose Samsung over HTC/Sony because Samsung has lot of stores and Service shops compared to Sony/HTC and Nokia doesn't offer Android.A Recent Appleinsider article stated that Apple gained 400% sales in India compared to last year only because unlike 2010 , Apple learnt a lesson and started to launch their products in India as quickly as possible with respect to US launch dates.There is a reason why i bought Apple into this - Profits they earn and also awareness they create for each of their products.Oh , Not to forget how better Samsung update cycle compared to other OEMs apart from Nexus series

Why wouldn't Samsung/Apple dominate ? when other companies are lazy to launch/advertize their products.