@YoWatShiinaEsq I think it IS a big city thing where strangers talk to each other easily.
This couple gawked at you because where they live is probably more homogeneous and they are not used to dealing with people who are different. But in larger cities, that people are different is given simply because there are more people.
Combined with the American tendency to be chatty with strangers, living in a large American city creates some very interesting opportunities to meet people.