Each of the 9 UC campuses is relatively small compared to the California population, so the admission competitiveness of the most desired UC campuses is high. Meanwhile, the 23 CSU campuses function as the broad-access and local-access universities around the state. In contrast, Arizona State University and University of Hawaii are relatively large compared to the Arizona and Hawaii populations respectively, so they can also function as the broad-access universities of their metro areas (and those universities are also located in the metro areas that have most of their states’ populations).
A counterfactual of California being like Arizona and Hawaii in this respect would be having perhaps three or four mega-universities of 150,000 to 200,000 students each located in the three or four largest metro areas of the state, instead of 9 UCs and 23 CSUs that it has currently. However, the California population is not as concentrated as the Arizona and Hawaii populations, so a greater percentage of students in this counterfactual would have to attend residentially instead of being able to commute at lower cost.