Yes, the mass transit, it is lovely. And it has been there a while. But not that long. Currently, Manhattan's population (as an island) is around 1.6 million. That's a lot of people in not very much space. But I read Luc Sante's entertaining _Low Life_. I know a lot of people have been in Manhattan for a long time. So many people, in fact, that it is actually kind of difficult to wrap one's brain around. Steiner didn't even try. If he had, he would have found this entry at wikipedia:
In 1900, there were 1.8 million people (as in, _more_ than now) in the same area. I'm reasonably certain that while _some_ of the current mass transit options were in place in 1900, it was nothing like as extensive as it is now.
I suppose the counter argument would be that Manhattan in 1900 was not "functional", but I think at that point, we might be into value judgments.