My theory is that the stupider the show you put on TV, the wider your potential audience is. Large viewer audiences equals more ad revenues, equals happy network executives.
British theater on PBS (sophisticated, high-brow entertainment): low viewership.
Big-titted blonde eating bugs on Fear Factor (stupid, but tittillating and gross): high viewership.
Your pie eating contest goes right into the second category. Low bugdet (unknowns eating pie is almost a zero dollar production), universally "appealing" (everyone eats and can "relate" to eating a lot of pie). Making a contest out of it provides just enough drama to interest enough viewers to make such a show a success. Sad, but true.