I went to Catholic school for grade school ( 1st to 8th) and on my very first day of public school, my eyes were opened. I never liked school, I never fit in (entirely my issue) and once in public school I found that I didn't have to attend.
Half the class was there for baby sitting - they were useless beyond constant disruptive behavior- one quarter tried but lacked the ability, the remaining quarter were able to succeed.
There were AP classes and such but the entire system is focused on improving the "success rate" for the oxygen thieves thereby never challenging the capable. You could get straight A's without much effort - I rarely went and when I showed up, I slept through most of it.
Sad! Fortunately I was blessed to attand Christian schools K-12. My parents sacrificed to make that happen.
I had good schooling and was mostly always challenged.