It’s the results of the Long March.
The schools are teaching what the victorious commiescum tell them to teach.
That’s the no accident part.
One common connector between the public schools and communism is the labor unions. That’s why their perfidy went on steroids in the ‘60s. But well before that communist activists and sympathizers knew well that control of education was key. From the “top” education colleges (e.g., Columbia) on down, they have formed two generations of pathetic teachers. And God bless any who make it through that gauntlet and then still try to teach eternal truths.