My assumption is that Brazil never adopted de jure segregation because it's just so racially mixed. Most white Brazilians have a not-insignificant degree of African or Amerindian blood, thus making an Anglo-American style One Drop Rule impossible (non-Hispanic White Americans are 98% European on average, with many having no Non-European DNA at all).
This is not really a correct assessment... Racial admixture between native peoples, Africans and Europeans did not occur as part of a sort of organic cultural movement, at least no more so than the same in the ‘US’. Rather, this racial mixing occurred through the lens and political mechanism of whitening, that is state mandated mixing of Europeans into existing African populaces recently ‘liberated’ from slavery. Meanwhile, said European migrants and plantation owners, were left as previously in a post-colonial society ran by them, for them. The opinions of the advocates of race mixing or whitening in Brazil, were not such that it was a policy of liberal values but deriving from their view that through racial admixtures, they could nullify the African existence and experience in Brazil and with enough European migrants and mixing, create new ‘whites’.