Honestly my bigger confusion are the fairly large swaths of NYC well served by the subway that still have more people using a car - most notably the area around Midwood in Brooklyn and Gun Hill in the Bronx area. Some of the anomalies make sense like the Upper East Side being more car friendly because of the wealth or the outer reaches of Queens just not having good subway access, but these places are neither wealthy or lack subway access
In the outer parts of the outer boroughs, cars are still useful for trips that aren’t to a CBD. To choose a random example, if you're a Bangladeshi family in Kensington wanting to visit relatives in Jackson Heights, driving takes way less than the F. Theoretically, IBX should help with this.
