If you allow anticipating, it's still open not ideal, ref will let some go that he thought were anticipated but were actually jumped and some pull back some for a jump that were not. Transponders are the best solution in my mind. Or a different way of starting races.
The worst ones are when a rider clearly mucks his start up and only hinders himself, but the ref stops it and gives him another go, does that happen in any other motor sport?? Not that I've seen.