This article 'Why are white people expats when the rest of us are immigrants?' made me think of the note above, which I once read in Oysteray Shopping Centre in Dar es Salaam.
I have to say though that I do meet Africans, who are expats (like in South Sudan).
My big time favourite category, however, are the expats who think they are experts. (Which is why I never became a member of the Dar es Salaam Yacht Club, and never felt happy about the expat term).