It stems from the fact that:
A. we live in a Eurocentric society and are socially conditioned to look down on pretty much any/all aspects that descend from the dark continent. Anywhere that Eurorpeans have touched or hold some influences, your bound to find this thinking. This is especially the case with those who are of Black/Spanish/Indigenous Indian descent. You guys have such a high European influence on your culture that I imagine (well actually its well documented ) colorism (which is intertwined with apathy of Africa somewhat) exists to a significant degree in your culture. The level at which it exists is up for debate, but lets not kid ourselves, it exists.
And it exists her in America as well, im not gonna lie. But at the end of the day, its pretty clear here in America that light-skinned or dark-skinned your a nigga. The effect skin tone that has on your life iin America probably could be gauged, but i'd bet money that the amount of which skin tone affects your life is much higher in Caribbean and Latin America countries (higher European influence and all).
B. The misunderstanding that "not relating to African Americans and their struggle"="Disowning of African Ancestry" . While I think correlation probably does exist between the two, they're not mutually exclusive concepts. Its very possible for one to be a very proud African and not stand by African Americans or even care for them. But imo, it's a very idiotic, douchebag-esque, and elitist way of thinking. Whether your from Botswana or Brooklyn, to the rest of the world, your a nigga. Our struggle is your struggle.
While it is quite natural to not see any common ground, it is quite critical that Blacks realize that pretty much every problem that Blacks worldwide face is the result of a singular attitude of " FUCK ALL THEM NIGGAS" and that until that changes, niggas everywhere are going to keep getting styled on. Seperating yourself, attributing the problem AA's do face to a deficiency within the people, and saying its not my problem only continues the cycle.
C. (ties in with B. but...)-A lack of understanding of nationality, ethnicity, and the standard of Race that the U.S. (and brazil) go by-Due to the fact that Brazil and the U.S. had the largest slave trades, we're two of few countries we're you'd never have to bring up your ethnicity/nationality.We mostly go by and identify by racial designation over everything. What im not saying is that ethnicity/nationality isn't important to many people here, it just isn't as much as a designator as it is in say Britain.
So with that said, its a tendency to assume that when someone born and raised in africa says they're not African American, they're saying so out of an assumed denunciation of their African ancestry. When the reality is they may feel that the term AA only applies to blacks born in America. Of course they also may denounce the term due to a low opinion of African Americans and a desire to not be confused with them. There's really no way of knowing.