Also, from watching a diverse group of colleagues and hearing migration process details, I have come to believe that, India has better diplomatic connections with most of the West compared to other APAC nations and the network of existing nationals are actually very helpful and large in most of the West, so they have much easier time moving, having initial support(very crucial when you just arrived and getting used to), information access and professional network.
Or to give a rather poor analogy for lack of better one, India has premium-business-class experience migrating to West, compared to other APAC, which are put through economy-saver class experience.