This isn’t unique to Google, same thing happened to me. Working for a name brand technology company in Atlanta, but am located remotely in the Raleigh-Durham area. My pay scale is “corrected” for the difference in markets and am payed a good 20% less than my Atlanta counterparts. By my calculation though, the cost of living in Atlanta isn’t near 20% higher than Raleigh-Durham… so not sure what else is factoring into that descrepancy.