In every metro area they've chosen, the vast majority of dwellings are single-family, owner occupied. So they can run cables above ground next to the existing telco equipment, and approach homeowners directly when it comes to installing the drop.

In Chicago, about 60 percent of the city is NOT owner-occupied. I'm sure New York is significantly higher. MDU runs are much more expensive, even with cooperative landlords.

As I said, if Google is not scared to dig - good for them. But they seem to want to avoid it. See their FAQ.