It goes on everywhere, I was referring to one city listed in an article. I've lived in several different states and my guess is at least 50% can work and that's being very generous.
Yesterday I saw a story on the news where a woman who has had cerebral palsy since 5 months old makes paintings by moving her eyes and the computer draws where her eyes go. She made over $14,000 for 1 painting! She works and she can't even move anything but her eyes.
I've worked with people in wheel chairs, blind, deaf and missing limbs but all of these people with bi-polar disorder and social anxiety disorder can't. 
Unlike Straw Man you seem to be a decent guy but I think probably a little naive when it comes to this stuff. I will work on converting you. 
Your certainly entitled to your guess as to how many people on disability are scamming the system, but it is still just an assumption with no way to prove it.
You must be determined to be disabled by the Social Security Administration (SSA) in order to qualify for SSDI or SSI. The process isn't a cake walk. Your doctor(s) must verify you are disabled. Then you'll need to hire an attorney who handles the lengthy process, including, reams of paperwork and representing you at your hearings before a disability judge. About
65 to 70% of initial applicants are denied. If you decide to pursue a reconsideration appeal your chances of qualifying worsens. Reconsiderations
rates of denial tend to be between 82-87 percent. Depending on how backlogged the Social Security Administration a successful claim for benefits can take a year or more.
If you are interested in knowing more about the processes involved in qualifying for SSDI, SSI, Medicare and PERS disability, let me know. I have some experience with these things.
Converting me to what? I have an open mind, so I am interested in learning more about most things. Keep in mind, if all you bring to the table is opinions, they won't be enough to change my thinking.