OP, those numbers are very likely. Median income in CA is 61k. UC’s have been adamant about accepting students of diverse socioeconomic backgrounds recently -which essentially means accepting more low/modest income students. A lot of low-income families are unaware of the meet-need private colleges, so they often look towards state schools. And if you’ve been brought up in CA, you’ve most likely been hearing about UC’s your whole life. So when tons of low-income CA kids get into UC’s each year with excellent aid, it’s very likely they will attend one over another college.
The way aid works at a UC: you either get it or you don’t. For incomes above 80k, there isn’t really a sliding scale for aid like some generous private colleges have. There’s the middle class scholarship -however, it’s not exactly a proportional/fair amount, thus middle class families most likely do not end up attending a UC. And upper class families probably don’t even bother to apply.