Originally Posted by Raymoland

As someone who stands at the door saying goodbye, I try to say something to almost everyone. Occasionally I do take a brief timeout especially with certain passengers, who for reasons I don't fully get, walk up the aisle and out the door without so much as a lookup. Those passengers are less likely to get at "Buh Bye", "thanks for flying with us", "have a nice day" etc.

If you walk up, make eye contact and say something, anything, I guarantee you almost everyone in my industry will say something back to you. So I would ask the OP, forget about race for a second, what is YOUR behavior as you walk up the aisle towards those standing there? That would give us more information about what might be going on.