Why are summer classes at CSU’s so expensive?

I want to take summer classes at CSU Fullerton and the cost of the credit is $330 (resident or not) The same with Dominguez Hills. Why are they so expensive?? I am a RESIDENT of CA. I am transferring from a CC to a CSU I just want to move forward and take summer. According to this site:http://www.csudh.edu/admfin/accounting_services/sfs-msrf-1314.pdf The unit [...]