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.