I live in California and you are exactly right. They're everywhere here, and from what I see, 95% of those sleeping on the streets have mental problems, drug problems, or both.
The "lack of affordable housing" line is a joke. These people could not make ANY mortgage or rent payment of any amount. What are we supposed to do, give them all free housing? Free on us, that is.
If the PTB were so concerned about affordable housing, they should have thought about that before they gave away all our good-paying manufacturing jobs to the rest of the world and basically destroyed our middle-class. IMO there is a direct link between hopelessness and lack of motivation.
Lastly, it doesn't help that the 9th Circuit's Martin vs. Boise decision has apparently been interpreted to mean the "homeless" can take over the streets entirely. The Western states are being flooded with vagrants, squatters, and undesirables now that the word is out that they're untouchable.
Off my soapbox now.