Judging by the sites you show in northern NY state, it picks up antennas and does not fully rely on satellite GPS. The iPhone App DATAMAN showed my iPhone accessed an antenna around Rome NY, many miles from Rogers and the Canadian Border, even though it was in Ottawa at that time.
Yes and no... I've actually been to that side of the St. Laurence, so it's not entirely off.
However, you are correct as the system only goes by GSM location, not Skyhook or anything like that, as you can see by the blank patch north of Lanark County - where I've definitely been all over.