While it’s true that public school teachers in the NYC area get good salaries and benefits, some districts are hiring certified teachers into teaching assistant positions and using them as teachers. That way they can pay them half or less of a teacher’s salary. In one such district that I’m familiar with, the teachers’ union officially represents the TAs but does nothing to benefit them.
Public school teachers in many places do not get good salaries. The average teacher salary in almost half the states is less than $50K.