Why would you hire an $80k Indian when you could easily hire an $80k American from somewhere with lower costs of living than Silicon Valley.
And you can find far more 80k level developers in individual cities in India than you would in a small mid level city in the US.
At some point where you live matters a lot. You can be rich, but if you can't get things shipped because the roads are bad, you can't get clean water, there are no local services around (haircut places, restaurants, tradespeople to fix your house), not to mention fun things to do, it looks worse.
I have this conversation with my friend Mike. I work and live in SF as a software engineer. He lives in Indiana and earns 8-10x what I do as a surgeon but I'm not sure he's actually better off. Especially considering there aren't great schools for him to send his kids to or interesting people to see in meetups.
Kids who grow up here are excited to bring their degree back close to their family. We have no problem relocating people from other parts of the US, when they need a job and look they realize our small city has what they need, and while the exact attractions are different and lesser, they are still good enough.
Who is paying domestically $80k or +$80k/year in India? Probably just FANNG.
I live in Canada and my assumption would be payroll & state taxes would be less in India compared to USA. There is also the advantage of having great leverage over a country when being a big fish in a smaller pool like in India.
From anecdotal experience, turnover is much higher in India. Changing jobs every 2 years seems to be the standard way of advancing your career and getting a good raise.