At many companies, they wouldn't necessarily notice the difference right away too, if someone was pretending to work. Management is often overloaded or checked out. Depending on ethnicity, they might also be unwilling to bring up the issue.

For example, if the patsy sticks with it, who is going to call the bluff - especially if no one took a picture?

They could claim the manager was being racist by not being able to recognize them or something. If someone IS not great at recognizing/telling apart, say, Indians, it could sow doubt that would make it harder to address. And that is a lot of people in the US.

The longer the delay, and the more legal buttons get pushed, the more the company pays out before the scam is over, and the more lucrative it is.