The testing wouldn't be necessary if the teachers were doing their jobs. The tests are, in effect, the rest of society asking "Why are ignorant 'graduates' being foisted on us year after year, given the oceans of cash we've spent on public schools?"
We simply can't believe that the teachers are, well, failing this miserably and consistently.
And no, the teachers aren't standing up for any students, only themselves. It's amazing how many continue to be taken in by that tissue-thin ruse.