I don't get the scam of paying someone in a wheelchair to be a relative, just that your group can get to the front of the line at Disney. When my wheelchair-bound aunt visited us, we had to wait in line, and she was able to wait near the front of the line, but wasn't able to get on the ride until we caught up. Perhaps since then, the line-waiting policy changed.
At other amusement parks, I never saw a disabled person get to the front of the line without waiting. I do not recall she was given boarding-first privileges to get on the airplane: I think she had to wait until everyone else boarded and then she and her care-taker were boarded. Made sense because she wouldn't hold up everyone getting on.
I have no problem with people with disabilities and babies being permitted to embark on planes first.
I wonder where Disneyland and Disney World got the idea that the disabled should be permitted to line jump? Because of the airlines' policy?