In school I felt I always worked hard, or was somehow more incentivized for the work than others. The harsh reality, apparent in hindsight, is that I was lazy and it came to me easily - as it does to many people. In teaching you one begins to quickly appreciate that inherent differences between children is absolutely night and day - and these differences emerge even as early as elementary.
These inherent differences are the giant elephant in the room that nobody wants to consider. In my opinion ignoring them and pretending that all we need to do is give more opportunity or money to some schools is doing us all great a disservice. A near majority of the kids in the classes I taught I could personally adopt and give them 24/7 attention and education at home and I suspect they would still fall well below the curve.
What is the solution? I have absolutely none. But at the same time I think that complete and open honesty and assessment is the first step to resolving any problem. When we start with false assumption as its more socially palatable, is it any wonder that we spend all of this money with absolutely nothing to show for it?