I know several teacher and can confirm this is true. If nothing else, where you work makes a big difference. The average salary of a teacher in california is about twice the average salary of a teacher in utah. Teacher pay is also often dependent on test scores of their students (which has its own problems, for example the best teachers might get assigned the worst students, because the teacher can help those students better, but that hurts the teachers test performance). The amount of education you have also makes a significant difference.