Grew up in the US. Have lived in Tennessee, Iowa and Maryland. Tennessee and Maryland were pretty crappy in comparison to the education I was getting in Iowa. Supposedly the county in Maryland (which I spent the most time in) was one of "the best in the nation", but I fathom how that could be true.
The problem with the Educational System in America, is really complex. Firstly, and probably most obviously, is that our curricula are chosen by politicians. As opposed to educators, or even people who would know "something" about education.
Another substantial problem, and one that is almost never openly talked about, is the idea that Certain Subcultures Within Our Population Have No Interest In Academics. It's not a simple question of "are they smart enough?" it's "how can I convince them to even care?".
They call this the Achievement Gap, and huge quantities of capital are being spent on closing it. Meaning, a very specific demographic is getting all of the attention while the vast majority goes ignored.
Now, regarding the issue of "politicians selecting curriculum", it should mentioned that the US has two educational systems. Private institutions, for the wealthy, and the Public Educational system. The children of the politicians invariably go to Private Institutions. It should come as no surprise to anyone, then, that funding for public schools has been gradually worn away, until you have situations like those in Philadelphia, right now, where you have 40 children to a classroom, and not enough chairs and desks to go around.
Edit: Regarding the OP, I don't think a "zero" or "no zero policy" would have any bearing on our situation because of the problems I've previously stated being to pronounced. It'd be like asking if I should drain the bathtub when my house is six feet underwater. Also changed the word "fact" to "idea", as the existence of the achievement gap is in dispute