The special class students have to make money for their own expenses on their own without outsider help, the reason is that if a mage got unlimited support, became very strong and then left the school without knowing how to make money the normal way they could turn into criminals, so they must be able to make money before graduation, I think is a good plot developent and it makes sense, of course they should probably told the kids about it before, at least they have some time before the rule is enforced.
The saint had the biggest hurdle as she lived for the church, therefore never thought about it as that would have been her "job", and like MC she have people that support him, for the academy rules she have to pay their salary too.