I would think that cost of living would have a lot to do with the salary. And, not all people have two incomes to work off of.
Re: having summers "off", I look at it more as a summer without the students and being able to set my own schedule. However, for most of us, summers mean going to school, planning ahead with units, etc. to save us some time during the school year. When you are a teacher, you will be very careful about saying you have the summer "off". It is a terrible misconception that the public has.