New Yorkers are not rude. They're just really, really busy. When you catch them on their, like, three minutes a day of downtime, they are perfectly ordinary, amicable people.
I once left all my souvenirs from One World Trade Center at a Shake Shack one evening and didn't notice they were gone until I was at the hotel. I called them and asked if they could hold them for me.
And they felt so guilty I had to make the trip to get my stuff back that they gave me a free soda.
They're not unfriendly, they just need to get where they're going. Southerners stop to interact more with each other. NYers are fine interacting, but not in a way that slows everything down.