Add in teachers' pensions, too, often matched by the state, or in the case of CA and some other states, wholly provided by the state. In other words, the state pays for the teachers' retirement, as opposed to workers funding their own 401(k). In CA, the "average" public teacher will get over $500,000 in pension payments over the course of their retirement, for "free".
Having taught high school before, though, I can tell you that the hours are as long as in the private sector, though the point about having the summers off is valid.
Same in Nevada. Additionally, teachers here don't pay Federal SS Tax, either, but can collect it if a deceased spouse paid into it. Pretty sweet deal (although they won't admit it).