I'm not sure about the cost. A lot of Mumbai's middle class housing is 30-40 floor towers. These are flats that sell for well under 200k, most under 100k. Labor cost is lower in India, but most material and equipment costs are not.
Another cost difference that you're not accounting for is building code. It would be entirely unacceptable for an SF skyscraper to fall down in a 7.9 magnitude earthquake. Likewise, fire safety is a huge factor in the US, and especially in California. Safe evacuation routes for people get more and more difficult to provide when the number of stories climbs higher, too.