When I was looking for work early this year I was told that most of the Google NYC roles were listed for internal transfers and that most of the actual hiring was in Warsaw (with 1000s of open roles, which I was told by Google recruiters at a conference in Europe)
If someone is transferring from SF to NYC they wouldn't have to advertise the position. I think the OP is referring to transferring people into the country on L1.
I was told that they were actually required to list them even if itβs someone transferring internally.
It was for a few specific ML research roles that I was interested in, of which there were very few in NYC and during the interview process I was told that they would go to internal candidates