[chubot]

Actually I just searched for "cost of living" and Bob See (a recruiter I worked with!) answered:

https://www.quora.com/Do-companies-like-Microsoft-Google-Ama...

Companies like the ones you've listed typically base salaries on "Cost of Labor" (for a given role in a given market), not "Cost of Living" (i.e. the price of a bucket of goods in a market) .

So that is exactly the misunderstanding here. People think the goal is "equal pay for equal work", or they think it's "cost of living". But neither of those is true -- it's a "cost of labor" adjustment.