I never got why if he got so far ahead that he could set traps and wait to watch him, he wouldn't just keep on driving and win. If I had to guess he bets against himself and the attempts to cheat are a means of showing that he is "trying".
The best part is when the OTHER drivers set traps in the same exact way as he does, all "THIS'LL CATCH OLE SNIDELY" and never get any karmic backlash for it
or maybe I'm thinking of Cannonball Run or something
Not so sure about wacky races, but i know laff a lympics had some "it's only cheating when the really rottens do it" thing going. Jet powered pogo-stick, cheating. Turning your pogo stick into a magic carpet with pogo sticks on the corners, not cheating.