On the one hand school is work. Who works? Those, who get good marks

I fully agree with this expression. The school is work. What do we get as payment? Knowledge. We collect the knowledge that we received at school like payment and then we use it in the later life. And those people who are trying hard to learn get more knowledge that they will use later. For example, at work or even early, on the exams that they will pass after school ending. So, the expression "the school is work" is a correct expression. At least, in my opinion.