The sanctioning bodies each have their own rules sets, but that does not mean that your local track adheres to them. Always best to contact your local track(s) and find out directly from them what rule set they follow and enforce.
That's most likely due to people playing with the grey areas or what they see as grey areas of the rules. There will be many times especially at smaller tracks that you will see stuff like the tech man also builds engines and his happen to win alot... the rules don't have as much grey as some like too say