'We are extracting free labour from employment candidates, it is great for us'.

Why not go a step further, and add a fee to become a candidate? Or perhaps just to skirt the queue and get to the front of the line?

Edit: Then there's the industrial espionage aspect but I don't really care about that, it's probably for the best if competitors and curious folks interview with them to learn what they have and how it works and undermine their business.