Many students who take course work during the summer months are surprised to find that they are required to pay a fee. There is a perception that public school is free. But that's not quite the case.
Public schools run mostly on tax money, and the amount of tax money they receive varies from one region to another. Schools have a certain amount of this money allotted to them, and they normally operate on a tight budget. This means any "extra" operating cost is not covered in the yearly budget. Summer school is usually considered extra, or beyond the yearly budget. Schools have to pay for the extra cost for utilities, for buses, and for teacher salaries.
This is why you (or your parents) are required to pay for summer school. If you have to attend summer school and you're not excited about it, the tuition just seems like an added blow!
Education is costly, but one thing is for sure: the lack of a good education will cost you a lot more in the long run!