Asian workers in my area can not or will not speak English.

   For the life of me, I can't figure out why so many of the Asian workers in my area can not or will not speak English. I am not racist nor am I prejudice in any way yet there are times while alone in a restaurant with the waite staff, all of whom are speaking to each other in Vietnamese, Chinese, or some other Asian dialect and not one of them will take the time to talk to me.
   I do not have this problem with other ethnic groups. For example, most Spanish speaking restaurants which I frequent the wait staff go out of their way to be friendly and sometimes when things are slow they will stop and hold conversations with their guests even if their English isn't so great.