Who counted these folks? Not the organization that sponsored it, mind you, but those that actually did the count--- were they independent or were they employees of agencies that gain more funding from high counts? And exactly how does one determine, without a professional evaluation, "mental illness?" 
At any rate, those that hang around downtown all day, spending hours in the library, are healthy and strong enough to haul 100# packs around all day--- but unable to do simple manual labor? Right.