Earlier quoted context omitted.
They're children, not some neural network you can train. They're all going to learn at different rates, and individualized education in a school setting is simply not possible. You're lucky if there's a breakdown by remedial, regular, and advanced classes. Even within those, kids are going to struggle and need some help outside of class time.
Is this “help” meant only to be available to kids with rich parents, as it is now? Or is the school at fault for not being willing, or able, to teach all kids to an acceptable degree?
You'd be even more surprised to learn that learning can happen anywhere, anytime and from anyone in any kind of form.
Helping kids at home with school work as a parent is not only accessible to rich families. You should help your kids when they really need it regardless of your socioeconomic background.
Now if you're talking about personalized/paid tutors outside of school, then yes - it's much more accessible to richer families but there is fundamentally nothing wrong that. What you decide to do with your kids outside of school is your choice.