I never had a music class at any point in school in California.

It exists in some California schools, but this is one of those things that exists because in some districts the parents setup a 501(c)3 whose only job is to fill the gap left by Prop 13 and Prop 98. My kid's had it every year, but in kinder it was a parent volunteer teaching it and in 1st/2nd the music teacher was entirely funded out of parent donations.