ironically, because of the very nature of the mentally ill, they are probably the least likely group to do any follow through that would help them become more functional - heck, they may have hopped a train somewhere  long before their next "appointment".  the meds maybe sold on the street or just tossed.   it's very sad because so many could be functional.  
but the way they do live on the streets directly impacts that immediate area for the worse.  I really see no respect for much. when something is always  given to you, it has little worth. some of these folks are very savvy and know how to work st vinny's, catholic services, hwy 99 warming center...even greenhill.  they tell their same, sad story, get a voucher and are set for as long as they keep what ever it was that they got. I don't mean to be cynical...it's just what I've seen.... 
 safe, temporary shelters are hard to come by and  is about as low as low- income housing on the "to do" list for the city