Why should teachers be a protected class?

The L.A. Times reports:

In 2003-04, the LAUSD had 747,009 students in its system, and those students were taught by 36,180 teachers. By 2007-08, the student population had shrunk 7%, to 693,680, but the teaching force had decreased only about 1%, to 35,785. In 2003-04, the student/teacher ratio was 20.64 students per teacher. In 2007-08, it was 19.38 students per teacher. If we went back to the 20.64 ratio of 2003-04, we would need only 33,597 teachers -- 2,000 fewer teachers than we have now. (Unions hate the thought of fewer teachers -- it means less money in the form of dues for them).

Heh.