Why is California SO attractive to high schoolers?

We’re in AZ and our HS Naviance always shows a big group of seniors applying to the UC’s. I think it’s based on a mistaken impression that they’ll qualify for financial aid or be able to qualify for in state tuition after a year. Eventually reality hits and so the Naviance stats also show that hardly anyone actually attends. I do know several kids who’ve gone to Cal Poly SLO but it’s a little more affordable than the UC’s.

Naviance stats from our HS for 2017
UCSB: 22 applied, 11 accepted, 0 attending
UCSD: 20 applied, 7 accepted, 0 attending
UCSC: 6 applied, 3 accepted, 0 attending
UC Davis: 7 applied, 4 accepted, 0 attending
UCLA: 32 applied, 4 accepted, 1 attemding
UCB: 20 applied, 8 accepted, 4 attending
CalPolySLO: 12 applied, 6 accepted, 1 attending