The problem that the UC system has with standardized tests is exactly that - they are standardized. That’s where they come in handy, when you are comparing the top students at one school against the top students at another school. It becomes pretty obvious when you see that the top students at an inner city non-selective high school are getting sub 1000 SAT scores, that they are not as prepared for college as the top students at good high schools who have >1500 SAT scores. They’re also useful for standardizing among applicants from the most prestigious schools, and just the best students at good public high schools. You should have seen the pitchforks and torches come out when I wrote on the Prep Schools website that it was obvious that there was grade inflation at some of the most prestigious prep schools, and that their students, on average, seemed to score no better on standardized tests than did the honors/AP cohort (top quarter or so) of a good suburban public high school. “Those tests cannot possibly measure how wonderful Buffy and Chip are!” Well, they can, and they do. That’s the problem.
When you look at the general scores of racial groups, certain groups tend to score higher than other groups. It’s not that the tests are biased, it’s that certain groups tend to be better academically prepared than other groups, and hence do better on the tests! Eliminating those standardized tests is simply a way of making it more difficult for the higher achievers to stand out, thus making it easier for the UCs to admit a more racially balanced class than the ones they admitted when they considered the SAT. Imagine if coaches choosing their basketball recruits could not consider height, or the athletic record of the applicants. They just had to go on the recommendation of the high school’s coach as to how good a player the kid was. It certainly would level the field for all high school basketball players applying for athletic scholarships. Going test-blind accomplishes the same thing. It levels the academic playing field, making the best student at the worst high school appear equal to the best student at the best high school.
The end result is either dropping the academic standards at the top institutions to allow those students who were not ready for the work to pass, or acknowledging that a significant proportion of those students admitted from the top of the class at a low-standards high school will wind up failing out, despite every possible academic support. It’s a disservice to those students, who probably would have done just fine at a less-competitive 4 yr UC public college. But it does achieve the goal of racially balancing the schools, without considering race, per se - just proxies for race, such as geography and socioeconomic class.