Bums and addicts need jobs too

The homeless are often told to get a job.  This relies on the following assumptions:

-Someone is willing to hire them
-They can perform their job well enough not to get fired
-They aren't mentally or physically impaired
-They can have an attitiude conducive to the work environment
-Substance abuse doesn't get in the way

Assuming none of those are true, what are some job choices for the homeless?

Do we realy need homeless/junkies/alcoholics? cant we just gass them or put them in camps or something?