Just because they're homeless doesn't mean they're street fairies, sweet and innocent and helpless or incapable of acting like a decent human being. Someone has been watching the Fisher King too many times.
The man talking to me while drooling spit the whole time was a very bad drunk. The gods know what he was drinking by them. Ever wonder why some of the homeless aren't in shelters? They don't want to stop drinking or taking drugs. Which the shelters don't allow.
Addicts basically. What can be done to help them? Nothing, until they want to help themselves. The people who want to be helped, are being helped as much as funding allows.
When it comes to the phenomenon of addictive substance abuse, there is an important distinction which needs to be made regarding addicted homeless persons. What motivated an addicted individual to come out of their gutter is when they realize that the pain of loss is greater than the perceived gain. Well, homeless folks have already lost everything. They certainly cannot motivate themselves by thinking about the pain of losing their spouse or children. Or losing their employment and their home as the result of their addiction.
Interestingly, organized groups reaching out to the specific category of substance abuse addicted homeless persons are usually manned by individuals who are recovered addicts (drugs or alcohol). They naturally experience empathy as a result and are not driven away by the "very bad drunk". They are very familiar with the loss of human dignity because they experienced it. They know which dynamics are at play. They do not give up on the "very bad drunk".
Switzerland did not give up on its ratio of drug addicted homeless persons. They took the very progressive measure to draw them into the system by providing them with drugs under a controlled environment. The condition being that such persons enrolled in the program do not use streets drugs any longer. It is an interesting out reach program and it is working. Once into the system, the dependency is then controlled by the system aiming to motivate rehabilitation and further social and economic reinsertion.
However, my being aware of "American exceptionalism", I am certainly not holding my breath on ever seeing your government emulating measures taken in Switzerland.