Some comment here on HN a month or so ago clarified this for me. It's more efficient to have a delivery truck go around to ten different houses than it is to have each of ten different vehicles drive from their houses to a central location.
Now if only there were some way to do that with people, not just with stuff (cough mumble public transit cough).
Rezone and densify, and build a mixed use walkable community of residential commercial and office.