Cost was a smaller factor than politics; the Indian government wanted the private keys for our certs in order to let FB put a POP there. That was an absolute dealbreaker, so we served India from Singapore and other POPs in nearby countries.
Regarding building a datacenter, that's much higher risk since it's a $100M-1B capital investment. I'm guessing both Facebook and Google see too much volatility to make the risk worth it. It could be an expensive paperweight if the Indian government changed their minds.
* They eventually will build one, but Indian consumers are (as of right now) less valuable to them (from an ad targeting perspective) than other geographies e.g. the economic/time/effort investment ROI is better elsewhere in the short term
* SE Asia (and their POPs there) have reasonable connectivity to India, so it might good enough for the time being
Both Google and Facebook both have datacenters/PoPs in Taiwan? I can't imagine the 24mm people there justify it, and both services are either largely unused or blocked in the nearby PRC...
I'm more surprised that Google has no presence in Japan, though.
They fixed that, at least for GCP. How the other Google bits fit into that, I do not know. They're planning to expand to a bunch of new regions this year.
More precisely, Taiwan is well connected by direct cables to Japan, China, Philippines, Viet Nam, Malaysia, Thailand, Korea, Singapore and the US. As far as I'm aware Google owns a cable connecting Taiwan with Japan (part of [1]).
Yeah, massive surprise for me to see Australia/NZ not have anything dedicated. Network reliability over the whole region must be pretty poor and although in population terms it's probably too low, you'd think in purchasing power terms it would still be worth it.
Map of Facebook data centers and PoP: http://imgur.com/dek8ESX