I'm gonna give a South African perspective on MULLATTOS/BI-RACIALS /HALF BREEDS or whatever we're calling them now.
The difference between the way white people "classify" black people has always been determined by the size of the black population relative to the white population...
During slavery/colonization here in South Africa black people faaaaaaaar outnumbered the whites
Secondly the Xhosa and Zulu tribes (that I'm part of) would not yield land, cattle or be enslaved and went to war with the whites, in turn whites "imported" their slave labor from Angola, Malaysia, etc in order to not create any future solidarity between these slaves in the Cape colony and the rest of the blacks in South Africa, White invaders came up with an ingenious system where they would classify the slaves who were not Zulu or Xhosa as "colored".. This Colored "race" classification was used to classify basically ALL mullatos and even dark skin slaves who simply were not Zulu /Xhosa
Whites did this coz their population numbers in SA were not big enough.
So instead of fighting the system /people that had enslaved them "Colroeds" were conditioned to see themselves as being better than those primitive uncivilized "Bantu" "natives"...
Interestingly the Dutch /Boers would take 30-40% of that "Colored" population that looked "white enough" to and marry or breed with them to further boost the small white numbers in SA.
Now in America INITIALLY the same was true, they did the same thing there in the early infancy of the slave trade and establishment of the early colonies, when the black slave population got big and outnumbered the whites (especially in the South)... They had distinct differences between a dark skin full African slave VS a Mullato... As the white numbers grew (and the black population was systematically stifled to remain stagnant) whites in the US once they established themselves as an unrivaled majority saw no threat in labeling ANYTHING with a "tan" as "Negro"...
It was simply a function of white rule.
The rule is simple.
If a white person is in a room with 10 black people, he/she must convince the lightest ones that they're not really black...
If 8 white people are in a room with a mixed breed and a 100% dark skin person, they can treat or consider both as "Black" coz collectively they're still an insignificant minority.
If you study the history of slavery here I think South Africa (Cape Colony), Portuguese slave trade in Brazil, French in Haiti, Congo, Ivory Coast, and ofcourse the English in America and the Islands you'll see this pattern ALL the time..
Lastly in Australia they commuted a genocide and wiped out the African population there, there's over 20million whites in Australia and are more than 90% of the population... Anything mixed in Australia is considered "Black", there are greened eyed curly haired mullattos claiming aboriginal status there and the white Australians allow it coz it poses zero threat.
Its always interesting to know the true historical context of these petty feuds between black people. Again i always sign off by recommending that every black person listen and read the work of Dr Amos N Wilson.
Peace from Cape Town
*I'll edit any typos later coz I'm typing on the phone and it's 7:30H here.