re: Coworkers or acquaintances who NEVER say hello first

You are talking about people you see everyday? Maybe it is just me, but if I see someone every day, throughout the day, I don't feel the need to address them every time I see them.

It really all depends on the situation as well. If I am in the middle of doing something I might not really be paying attention to exactly who is passing by. If I see them in passing, I will casually address them "what's going on today?" "everything going good?".. some bullshite like that, but I don't think formally addressing people every day is necessary. In some ways, I think there is some awkwardness in formally addressing.. going out of your way to address people you see every day.