Or, in the fraud case, "books will be audited at frequency X", "Y behavior makes it too easy to hide fraud and is not allowed". Rather than "fraud is illegal on Monday", "fraud is also illegal on Tuesday", "fraud is even illegal on holidays"...
Of course we can never achieve 100% with more regulation, but we make it more of a priority to make abuse harder to get away with than elsewhere, presumably increasing overhead in exchange for lowering abuse (yes, this is probably not a strictly linear curve)