The school system functions perfectly fine. All this bullshit of "it was based off of a bad system" is bullshit because 90% of states in the world are based off that "Prussian" model. The Chinese do good in school "despite" their education being focused on loyalty to the communist party, and the Japanese, Russians and every other country does well when their model is focused on loyalty to the state.
there is another factor. When you look at the grades of European Americans and compare them to the grades of Europeans there's basically no difference; Europeans do as well as Europeans. When you compare black and hispanic grades to their counterparts outside America you, unsurprisingly, find that they do the same.
The reason American school grades appear to be lower is that America has a large dark population compared to Euro countries who are mostly ~80% white. You sucking in school has nothing to do with the system you were taught under. If you suck in school it's your fault, not the "system"