Fundamentally, the answer is in Hansard of the 1930s. It was too politically sensitive a topic, so they left it to be decided by common law. Unfortunately, over the past 30-odd years, the evolution of common law in the area has stopped. So we are left with law that is quite old and is not evolving to meet our definition.
If I might add just one more thing, the U.K. had a similar issue—we've been relying on their case law—and they have actually legislated the definition.
So we're stuck.