Sure but San francisco also have commuters and tourists. It is difficult to get those numbers vs residents. If you were to critique this statistic than you'd have to do the same for SF

SF has a very sizeable population commute out everyday though, or at least did pre-COVID. Commuter traffic was worse in the leaving SF direction when I was there. For NYC and especially Manhattan it's practically a joke to consider living there and commuting out everyday. So I'd guess average simultaneous foot traffic is way more underestimated for NYC than for SF.

In my brief time in SF the only tourists are on the Powell St team or at Fishermen's Wharf. It's really a contrast with many cities where the tourists tend to scatter more widely. The streets of San Francisco are really bare of people comparatively.