I imagine they're getting decent bang for their buck when hiring in NYC. Really the COL adjusted wages in NYC are some of the lowest for all American tech cities.
...except (at least for Amazon) they pay more in NYC, and of all companies Google doesn't exactly exercise frugality wrt compensation.
If levels.fyi is any indication, Google NYC comp is only marginally lower than SV, if at all.
Why would they care about getting a good bargain in “COL adjusted wages”? Even in NYC there is not a currency exchange Google can go to to turn $100k Florida dollars into $200k New York dollars.