NYC is about an order of magnitude larger than SF in many different ways - for example, total population (8.6m vs 880k people) and area (302 vs 46 square miles). So comparing absolute number of homeless people between the two cities is not likely to be a useful thing to do. Your link does however demonstrate that NYC has a slightly higher percentage of homeless population than SF - .9% vs .7%. So I tend to agree that there's something else that contributes to it being a larger conversation in SF than NYC beyond just the number/percentage of people.