Because it's a random axis to split the data on and you only do it for the US, which makes zero sense to do when comparing entire countries.
What about Tunisian immigrants in France? Maybe they'd be at the very top? What about Whites in all countries? Maybe White kids across the globe are better than White kids in the US, which would put the US at the bottom?
We cannot conclude that "US education is amongst the top in the world" from the chart you presented.
Because it's a random axis to split the data on and you only do it for the US, which makes zero sense to do when comparing entire countries.
What about Tunisian immigrants in France? Maybe they'd be at the very top? What about Whites in all countries? Maybe White kids across the globe are better than White kids in the US, which would put the US at the bottom?
We cannot conclude that "US education is amongst the top in the world" from the chart you presented.