“I can’t imagine any student applying to UCLA because they think they will get in, but then NOT applying to Berkeley because they don’t think they will get in. That just doesn’t add up to me.”
If you look at the applicant stats (https://www.universityofcalifornia.edu/infocenter/freshman-admissions-summary) of HS GPA by campus, significantly more students with a relatively low GPA (below 3.8 weighted) apply to UCLA and have little chance of getting in (they account for less than 5% of admitted students). The % of freshman applicants with <3.8 weighted GPA for each campus was:
2017: UCLA 33% UCB 27%
2016: UCLA 34% UCB 27%
2015: UCLA 36% UCB 28%
2014: UCLA 37% UCB 30%
2013: UCLA 39% UCB 32%
2012: UCLA 41% UCB 34%
The absolute number of lower stat applicants would show an even greater disparity, since UCLA has more applications in total than UCB. So it looks to me like many people just haven’t realized how selective UCLA is. But that may change in the future with the publicity about record low admission rates.