The long waiting times are partly due to how the SSA considers a “disability” in the first place. The Social Security Act identifies a disability if it renders a person incapable of working for at least a year and especially if that person is unable to find other work because of it. Death due to the disability is also considered. In addition, the Act doesn’t have any provisions for partial or temporary disabilities, which means that people incapacitated for six months or so are better off relying on worker’s compensation, veteran’s benefits, and the like.
In addition to the strict requirements for Social Security disability eligibility, disability claims can be rejected due to other reasons, like if the applicant only listed various impairments instead of a main problem or if it’s discovered that he or she was able to go to work for a short time even with the disability.