dunno
Funny, when I was a kid Flatbush was known for everyone saying good Shabbos, and they used to “knock” Boro Parkers for not saying good Shabbos. Now Flatbushers dont say good Shabbos either?
I agree with you all Jews should wish each other a good Shabbos, I try to do that and I end up getting the looks from some people, utterly ignored by others, but I will say more than half answer with a nice good Shabbos.