How come a workstudy "income" doesn't count toward public housing?

I go to a community college, kind of far from my house and I don't drive so right now I'm taking online cles but i really want to move up there to take clroom instruction cles and I currently have a part time work study job and no other income not even gov't istance. I've been on a HUD list for a year ( I signed up out of desperation), they told me I would have to report the income but it would not count but why doesn't it count?