The problem is the skills and communication, which stem from this situation being the status-quo and there being nowhere for new developers to learn anything better (or even know that their current skills aren't up to scratch, at least not for working on foreign, outsourced projects).
The real reason is that their country of origin just has a massive number of people, and the ones who are able to immigrate to the US are those who have either money or skills that will make them money here. Same goes for Chinese Americans.
There is a source country with a massive number of people, and the target country (with a fraction of the residents of the source country). The target country filters immigration for high skill and/or high income. Just through the sheer numbers game, you get the outcome you described.
Of course, it is more nuanced in terms of the overall development level of the source country (e.g., this probably wouldn't work if pretty much no one in India was able to afford a computer or if India had almost no internet connectivity). But with how high the Indian level of development is as a country (compared to the minimum required for the numbers game to start working), it shouldn't matter.