The real problem will never be solved because it will never be named. I will probably get flagged, dead just for writing this. Whites and Asians in America perform far better on PSIA than the international average; the American Asians better than Asia, the whites better than Europe, mostly.
No, the inconvenient truth of the matter is that american blacks (and Hispanics? Not sure) drag down the scores. This score, and every score that we have yet devised. Every measure of intelligence that we can think of, every control for income and parents, every statistical trick to attempt some socially acceptable explanation, it all comes up the same way: they're just not as smart. The natural attempt to handwave this as some kind of systemic racism is thwarted by the existence of those poor Asians who perform better than whites; this is another inconvenience and is why Asians are being quietly dropped from "PoC" initiatives and measurements. Californian education reform is all a song and dance to desperately ignore this fact. When you have a group of people who are less smart, and the goal is that they achieve the same level as everyone else, what can you do? Well, you can give them more class time and free tutoring, but no one will support an initiative where some students take extra classes. There simply is no solution apart from lowering the ceiling. And since the governing bodies refuse to stop measuring everything by race, they also refuse to simply segregate based on ability, since this would show too many blacks in the lower performing classes.
This problem will literally never be solved under the current mode of thinking. It can't be, because those in charge are adamant about rejecting reality. No solution can be had if the problem cannot be identified. They will continue lowering the ceiling, and they may eventually lower it enough to get an equitable result. But those pesky private schools and tutors will still be around ruining their plans, and if there ever still exists a high educational standard out there somewhere, it's the tutored and the private schooled who will pass that bar. And at that point then it actually will be because of privilege.