I have always felt that the biggest divide is the value that is placed on education rather than the value that is paid into or for that education, and it isn't necessarily the "fault" of those who do not value it, by and large. They've never seen, much less received the payoff.
The private school customers, for instance, value the idea of "education", regardless of what that "education" means to them...whether it means access, real learning, social status, etc. They value it and therefore invest time and money in it.
We have an entire segment of our society which sees little to no value in earning an education, and therefore we are left with these un-invested parents and subsequently under-invested students. They have no relatable and real-life examples in their life who are demonstrating the benefits of an earned education. Often, the only examples they see of success are the antithesis of those who achieved through hard work in the educational system. An education is a stigma and not a badge or honor, much less an expectation.
This divide spans races and parts of the country. Certainly there are examples of kids rising above this in spite of their parents and community, but those are far too rare.
Until our societal system changes the perception in those communities and demonstrate in a relatable way that an education and life beyond is preferable to their current situation, we will continue to have teachers and entire school systems bailing water and saving few while losing the masses to a self fulfilling prophecy.