Ha ha, yes, we do like to sport brand names. And as for colder climates, I mean, what's the point of wearing this stuff where no one will see you?? Seriously, though, new yorkers do tend to spend more time outside than residents of other places. For one, we walk a lot, for another, if it were any colder, we wouldn't walk so much. Not that that necessarily is true of you and certainly not that it has anything to do with why anyone would need an $800 coat vs. a $200 coat.
Bear in mind though that we also like cheap knock-offs, so some of what you're seeing may be from Canal St.