You're both half-right. due to the state and county segmentation of education, union influence and educational job security varies widely. In places like New York, unions are very powerful and dismissals are difficult. In some places, it's far easier.

Likewise, some places have very high academic standards, and in other places creationism is considered a valid element in science currricula. Academic quality is not strongly correlated to unions' bargaining ability, as far as I can tell.