Many times I actually get no reply even when I say "Assalamu alaikum"! They are Arabs and obviously Muslim ladies(abaya and niqaab etc) and yet when I greet them with what Muslims consider the best of greetings they give me the blank stare! Sheeeeeesh....mind you I cannot say they are being discriminating cos afterall they can't tell my nationality since I wear niqab too. Some people just lack knowledge,manners, and social etiquettes..period! 

That said I believe we should continue being our polite selves and maybe Inshallah inspire others to be more polite too.