That said, I don't think it's entirely wrong to think that if you send your child to school for 6-8 hours a day, they should actually come home having learned something.
I didn't have helicopter parents, my parents just watched for grades. No PTA meetings, no reviewing my hw, no private tutors... I grew up and went to schools in the hood, but still got great grades, took a dozen AP/advanced courses, was in IB, got into an ivy league college, etc. etc.
So there was definitely something going on at school with regard to student expectations, curriculum, and teacher quality (I had amazing teachers).