That's just for the academic year.
Then they work during the summer in preparation for the next school year, teaching summer school, attending their own continuing education courses or graduate courses, or working a second job to make enough money to make ends meet.
And most professionals do work more, but not hugely more. I'm in a middling org and get 50 days off a year between holidays, PTO, and sick leave (not always used, rolls over though). If I used all my sick leave I'd only work 210 days, just 30 more days than a teacher who manages to take the entire summer off. At a middling org.