"..I'll take a wild stab and say recent immigrants has a significant role"
I feel certain that a high percentage of recipients of social security disability payments are fraudulent. I handled workers compensation insurance claims for an industrial plant for a number of years in addition to other hats of course, and it was always a battle to get them off WC and back on the job. Back injury claimants were the worst to handle especially when you knew they were working under the table jobs which proved they were OK to go.