One of the big reasons for the stupid size of parking lots around stores has to do with zoning laws as well. I don't remember the numbers and it's gotta vary by district, but it's tied to a certain percentage of the max occupancy of the building.
Because of the car-focused infrastructure that puts everything else last, we've created a self-defeating system that forces people to drive everywhere, thus justifying the massive parking lots that prevent people from using other modes of transport in the first place.
Both? Both. Massachusetts is right up there as well, and while Boston isn't as large or dense as NYC, a full 50% of the workforce in Boston commutes every day using the T. That's a huge portion of the people who go into and out of Boston daily from outside suburbs and towns who aren't on the roads.