I was curious too - and skimming the ADVChina list, they have a video about this. They said that it’s called that because the job is so simple a monkey could do it, and the only reason you got the job was because you are white. That’s where the term comes from. (Though later they said the term applies to all jobs like this, including non-white foreigners).
They go in to some more detail of examples of basically being hired as set dressing for meetings, to show the company is more international or has foreign interests or “this guy is the architect for the project” even though he’s just some guy in a suit. Straight up lying, basically.
If you want to watch an American and South African white dude drive around China talking about it, link below. Both are English teachers in China, but both did a side gig sometimes and talked about it, as well as know other people there doing those jobs.
