When looking for a home in the NYC metro area (one of the wealthiest in the country), I was absolutely appalled at the quality of the schools in 90% of the places I looked. As an affluent person with the means to choose, I chose to look elsewhere. The experience got me thinking, however: 90% of people go to terrible schools because they don't have a choice.
Taxes are continually cut. Districts are gerrymandered so the most residents don't get an equal say. Interest groups take over local and state politics and de-prioritize investing in the future in the name of profits and short-term political gains. If nations grow great when people sew the seeds of trees in whose shade they will never sit, then we're in the clear-cutting stage of our society.
This study provides quantitative evidence that something is wrong with education, but there is qualitative evidence as well. The frequent politicization of events and susceptibility to fake news indicates a lack of critical thinking skills.