Perhaps you might want to explain to us how those kids are helped in the regional finals which give the free entry to high school?
The competitions on a regional level are organised by teachers from the region - it's impossible for there to be corruption due to the way that it's all done. About the only issue is that at the school level, the children who have the same teacher as the organiser in-school will do better - but that's obvious!
I'm sorry, but for commonsense reasons I can't be more specific ... I have teenage kids!