More broadly, why is there so much emphasis in school on covering only African-American segregation, instead of covering that as well Latino segregation in California/western US, etc.?
Again, I realize I probably sound horribly racist, but, as a history major, this is something I've been thinking about lately.
This is a great question. I am very pleased that when I was chairing the National Historic Landmarks Committee for the National Park Service, we were able to list the Los Angeles’ civic center, the U.S. Courthouse and Post Office, granting a level of national recognition to the important story of Mendez v. Westminster. See also this site. Besides the differences in the two cases, eloquently addressed by /u/MdDowntown, there are other issues.
Mendez v. Westminster was an important building block in the evolution of the Civil Rights movement. It persuaded the African American community to stop its efforts to develop a truly equal formula in a separate world where the "equal" was lagging significantly. This important California case shifted the emphasis to challenge the entire separate-but-equal doctrine as intrinsically unconstitutional.
Of course, by framing the discussion of Mendez v. Westminster in the context of the African-American struggle, we shift the reason for the significance of this case away from the Spanish-speaking community to a question about how this case affected African Americans. This yields the same disparity in emphasis that your question asks to be addressed. I argued in the development of this landmark nomination that seeing this case as important to the Latino story should be sufficient for granting the resource National Landmark designation. That said, the entire National Park Service Landmark apparatus tends to see everything through the lens of the Atlantic seaboard. The staff does a heroic effort in trying to make this NOT the case, but they live and work in and near DC, and they are for the most part easterners.
In addition, African Americans represent the largest and most significant minority for most of the national story, and this is particularly true in the East. So some of the answer to your question is a matter of East v. West. Some of it is in the fact that African Americans were the most significant oppressed minority for most of American history. The Latino story is general both western and late to emerge in significant numbers.
Sec. Ken Salazar, the first Secretary of the Interior under President Obama, was wonderful in the way that he directed the Landmarks program to begin an initiative to find resources that spoke to the Latino community and its history. I would expect that the story of cases such as Mendez v. Westminster will increase in importance as we tell and retell the national story - particularly through its historic sites. But the disparity that you question will continue until we all do what we can to correct the imbalance.
Brown was a sweeping change to long-settled precedent (Plessy v. Ferguson), which for 60 years had allowed "separate but equal" facilities to satisfy the Equal Protection Clause.
I'm not aware that there was ever de jure segregation forbidding attendance by Mexican-American children in any US schools, though local customs and residential patterns often had exactly the same effect. Racial zoning had already been declared unconstitutional in 1917, and residential racial covenants had already been made unenforceable in 1948.