"The same holds for the contract you have with a school."
You can not have a "contract" with the school. The student is being coerced, to a degree not dissimilar to a prisoner. (I am not saying that a student is exactly the same as a prisoner, because I can think of many relevant differences, I'm just saying the coercion level is similar; it is unilateral, the scope is huge, and there is no way out for most of it.) The concept of "contract" is not relevant.
If you think cheating is bad only because it is a violation of contract, then cheating is not bad. (You may not agree with the word "only"; I am making a logical statement here. If you think it's bad for other reasons, as I do, then that does not falsify that logical statement.)
As another commenter suggested, there is a stark difference between high school and universities. high schools in the US can be justifiably compared to prisons in this sense, but universities cannot.
I think the comparison with prisons is pretty bunk. Students and their parents get to choose which school they'd like to attend; for many people, that means an enormous amount of school choice. With home schooling in many states and the GED, students have still more choice. And of course, you're free to drop out -- you just have to be willing to accept the consequences.
You can not have a "contract" with the school. The student is being coerced, to a degree not dissimilar to a prisoner. (I am not saying that a student is exactly the same as a prisoner, because I can think of many relevant differences, I'm just saying the coercion level is similar; it is unilateral, the scope is huge, and there is no way out for most of it.) The concept of "contract" is not relevant.
If you think cheating is bad only because it is a violation of contract, then cheating is not bad. (You may not agree with the word "only"; I am making a logical statement here. If you think it's bad for other reasons, as I do, then that does not falsify that logical statement.)