I always love when someone complains about this “problem”.
I’ve been living in Flatbush since the day I was born, and although I would love nothing more than to move OOT, I can honestly say I have never experienced this phenomenon.
Whenever I am out on Shabbos and pass anyone I greet them with a smile and a “Good Shabbos!” and it is like-wise reciprocated.
Obviously, if you are a female and are greeting a Chassidish male who is already looking at the pavement, dont expect a greeting in return. Qualify your buyer.