I'm guessing it is a cost related choice, and the lock only needs to be as effective as a regular key lock that can also be opened easily using one of a number of different tools and techniques (picks/rakes, bump keys, tin or plastic cut-out clones, key guns, etc).<p>The fact that you have to unscrew and open it to expose the vulnerable bits means it is at least that much safer than a key lock, which doesn't mean very much since they are both easy.