How can you pass a math test without understanding how to do math problems? I guess if the teachers were teaching students to remember the correct multiple choice answer before the test, that would be a way to scam the system. But I don't think that's happening and if it is, that's more of a reflection on that teacher than the program. I think I understand your larger point though. And my question is, if the test represents material students should know at their grade level, then what is wrong with "teaching" towards the test. If I know that my students are going to be tested on biology, I'm going to teach them biology. If the test isn't representative of what children their age should know, that is a valid grievance. But we can change the test without scrapping the whole system.
Teaching to the tests means placing emphasis only on Math and Reading, as those are the 2 subjects tested. There is no assessment of any other subjects for the purposes of standardization. That means it is up to the school and/or teacher whether they try and incorporate other subjects into the curruculum, but for those schools focused solely on test scores, they don't have to. In theory this means a child may graduate from 5th grade with very little education in the way of science, geography, or any other subject apart from math and reading. That is the main reason many classify it as a failure as the goal of improved test scores is often not achieved by including the best educational practices.