You can argue that NYC is a better place to meet women than SF, but is it really because there's slightly more women than men in the general population? I think it's due to a variety of other factors:
Different mindset of people in NYC than in SF (compare NYC's finance and fashion industries to SF's technology industry)...
Better logistics in NYC than in SF (in NYC: 24/7 public transport, plenty of taxis, no car culture, and apartments nearby; in SF: BART isn't 24/7, taxis scarcer, many have their own vehicles, and people live farther)...
Different mindset of people in NYC than in SF (compare NYC's finance and fashion industries to SF's technology industry)...
Better logistics in NYC than in SF (in NYC: 24/7 public transport, plenty of taxis, no car culture, and apartments nearby; in SF: BART isn't 24/7, taxis scarcer, many have their own vehicles, and people live farther)...
What else?