Is there a functional difference between places that have a front-desk person and actual doormen, besides opening doors? Not that the former is super-common in San Francisco either, but it's at least existent.
My main dealings with them were, in my most-cash strapped days, delivering Postmates orders to their buildings. They also serve the valuable service of not having to explain to the delivery guy how to get into the building. Much longer notes from the people whose buildings were not manned.
