Urban environments blunt people's connection to other people too, see
https://en.wikipedia.org/wiki/Murder_of_Kitty_Genovese
If you pack people in too tight they just tune each other out.
I mean, the very first paragraph of your own link says: "However, subsequent investigations revealed that the extent of public apathy was exaggerated." and the second paragraph says, "Researchers have since uncovered major inaccuracies in the Times article, and police interviews revealed that some witnesses had attempted to contact authorities."
That's my neighborhood you're "citing". It's a walking neighborhood--cars are useless with no parking next to stores. I talked to more strangers there than in any other place I've lived. My doctor would stop me on the street to look in my grocery bags.