Class funds are not compulsory BUT it is only used to benefit the whole class who can go. The donation is compulsory and that atlas 80% of the class population (20 students) should attend planned activities/bonding session. All to contribute and that those who can not go is their own lost. You do NOT have a free will to choose to donate or not.
Class funds is an item that shows the amount of effort and determination put in by the students of the class. If you were to say that this effort is communism or saying that you have a free will then I have nothing to say but you have zero trusts in YOUR own class. Understand that by helping donate to class funds, our sub conscience mind will believe that you trust the EXCO members to use the money to good use.