It has to do with asian population also. They tend to look away, and not stare, or feel uncomfortable with it. Since asians are about 30-40% of the area, it sets the tone that eye contact is rude.

NJ is the same. I work near the city in hoboken, people on the PATH (train between NY and NJ) are always staring at their smartphones. I was sitting in the PATH the other night though, and two guys started a conversation with me about my droid, if that counts...

I live in suburbia in NJ though, which is pretty different. When I'm out running or biking I try to say hi to other pedestrians and they typically reciprocate.