I live in NYC, and I know a few people who get SSI, SSD, and Home Relief. I find it very difficult to imagine any of these people being able to get a job. they either have severe physical or psychiatric disablities which prclude them from getting a job.
My ex-roommate might be an exception. If she got an operation for her leg which goes out on her at unpredictable intervals and some psychiatric help she could use her outstanding office skills to get a good job, but her Mediaid provider has been able to postpone and postpone the needed knee opearation for five years, and she is also unable to get needed psychotherapy.
Others on SSI include a lady who when I met her suddenly asked me, "Are you a witch?", telling me a lot about her emotional state.
Another friend of mine on SSI was a bicycle messenger, but he cannot do this work anymore because, since he got out of the mental hospital, he flies into rages at things which would not even be noticed by normal people.