According to the NAACP and the Supreme Court, why were "separate but equal” schools unfair?

The "separate but equal schools" were unfair because they were never actually equal

Explanation:

Amenities for black were always way worse than amenities for whites. Rusted water fountains, dirty bathrooms, not always getting a good quality education, etc.., so they were separate, but never really equal.

In the pivotal case of Plessy v. Ferguson in 1896, the U.S. Supreme Court ruled that racially separate facilities, if equal, did not violate the Constitution. Segregation, the Court said, was not discrimination.

Explanation:

So it's basically saying if what people did was wrong but it was among equal, it wasn't a problem since it's not violating the term of equal.

Are you Australian? In that case it would rather ironically be the Aboriginals and their children. If not, (and I'm not 100 percent sure about this one) but this was during the time period of the African American rights Reform period in the United States.