From today's NYT: What People Buy Where — Link here.
A friend suggests that the NYC data stem from the fact that so many social interactions are in person, due to the crowded nature of the city, especially Manhattan. When you meet (or otherwise interact) with somone in person, your big, expensive watch (for men), or purse/bag (for women), is a clearly visible, strong signal of weatlth, success, etc. When the population isn't as densely packed, you can't tell (as easily) that someone is wearing a $10,000 watch or clutching a $10,000 purse/bag.
No idea if this is true, but an interesting hypothesis to test.