For math level 2, the purpose may be to screen out those who do not know math through precalculus that well. I.e. the only way to distinguish yourself is in a negative way.
Remember that math level 2 takers are a self-selected group of students who are strong in math (at least one grade level ahead) and who are applying to more selective colleges that are the ones who want subject tests. So lots of them know their math through precalculus quite well.