Well since the whole point of those local exchanges is to provide a method of purchase for local people to buy bitcoins, they do whatever they want.
I mean literally they can buy coins off other exchanges (1 btc = about $2400 on coinbase) using any international bank wiring or whatever (as they sell it for more than $3000).
I don't know how banks work in India but maybe these exchanges don't accept money from local people so exchange owners use this to put their own rules/prices.
They have stated that they don't buy bitcoins from international exchanges.........I read this somewhere.