Mature Metal discussion

I placed an order for a Jailbird device about seven days ago, and I likely still have the option to swap my padlock version for one with security screws. My main question is: how exactly does that screw mechanism function? The picture displays a threaded fastener. Given the price difference—$65 compared to $8.95 for the standard padlock—and knowing that replacement keys aren’t sold separately, I’m curious about the specific locking method. Are there internal tumblers (it doesn’t appear so), or is it just a regular screw with an unusual head shape? If you need a special driver bit to unscrew it, why can’t you buy extra screws? Hmm, surely there’s a straightforward answer that might seem obvious once stated, but I’m drawing a blank. Perhaps each screw has a unique head design meant only for its specific unlocking tool? But then again, why are replacements unavailable? I expect the simple truth will make me blush, though as they say, “there is no such thing as a stupid question” ha-ha. Hope you recall that advice…