I was surprised how low AC usage in residential homes is in LA compared to many cities on the East Coast. I guess that a city which is rather hot year-round has less need for AC compared to cities that are very hot for only a few months per year. It allows building differently.
At least for the first one, this definitely plays into it. Average winters in NYC top out at 38-42 degrees, compared to LA bottoming out at 48-49. LA can get away with less insulation, so they don't need to worry about buildings trapping as much heat during the summer.
High energy prices could also play a role.