You don't need a citation to counter a baseless assertion. My assertion is that most people who apply for remote jobs are fairly honest (by culture) white-collar types who wouldn't think to 'double up on remote jobs' for the same reason they wouldn't think go out at night stealing catalytic converters, which is that they possess a basic sense of right and wrong.
I mean, if you think that the average person is basically a scammer at heart, okay... Maybe you come from a low-trust culture, I don't know. I don't think most people who come from high-trust cultures would behave this way or think that behaving this way is okay.