That, however, does NOT favor the rich, mod cheating/forgery, which surprisingly does get caught, due to the widespread expectation of the system to be fair.

And there used to be bonus points for STEM Olympiads, which had totally worked as intended by providing a sound alternative for the talented / hard-working specialists who have not so much family backing. There were varying degrees of cheating (mostly in the form of leaked problem banks), more rampant in some provinces than others, but AFAIK the asking price was not totally out of reach for the common working family, so it'd be unfair to say cheating the exam favors the rich either.