It's basically that payment flows towards the core of the network, which is Europe and America. If you're the first Indian ISP, you have to pay a European ISP for an upstream connection - they won't pay you. And that persists and becomes "just the way things are done". It can only reverse if there are significant websites in India that Europeans want to access, then the European ISPs will be getting more value than the Indian ones and the Indian ones will be able to demand payment.