Instead of admitting the captain of the ping-pong team (who can't count past 21 - or past ten without pulling off his boots), maybe admit any one of the students who... Did not have the extracurricular pedigree, but actually applied themselves and passed Math 12?
Surely, there's more than a few hundred of the latter in California.
Seems easy to explain, high schoolers were not in school from 2020-2022 in most areas, so they were two or three years behind in everything when they got to college.
Oh, wait
Freshman admissions at UC San Diego are for a different group. They have a 28% acceptance rate, not the most selective in the country but far from taking anyone with a pulse. The admissions office intends to reject people who doesn't know how to do basic math, letting them know that this isn't the right pathway for them, but they're not able to do that reliably without standardized tests.