I also live in California and I also send my child to a private school which costs upwards of 30k.

California currently spends about 10k per student for public education. That makes 30k sound crazy, but in 1970 California spent 5500 which is about 35k in 2017 dollars. California (and most of the US) is woefully underfunding it's schools.

Public schools also cost about $20k/year/pupil (I wrote $30 before but looks like I was mistaken). But this is paid from general budget so nobody cares too much, because tax money obviously aren't real money.