WIY: Not sure which neighbrhoods you hang out in. Definately not the klal. According to your reasoning it really depends on how people act. If people in a community say good shabbos to flirt than it’s assur, and if not then it’s muttar.
Great Story- I know a nice middle aged Orthodox man, who wished good shabbos to another Orthodox man while crossing paths in the street. When the other man did not respond the nice man repeated good shabos. When the other man didn’t respond, the nice man said “excuse me for assuming that you”re Jewish.”