It would seem to the average person, there should be something prohibiting a person from attaching a weapon to a drone.
This has been coming for decades, and yet governments have been far too busy lining the pockets of members of the party in power to do anything about it. Donald Kingsbury predicted home-built cruise missiles in the '80's (in "The Moon Goddess and the Son").
It's been obvious since the early 90's that computing costs and hardware costs were falling so rapidly that anyone could do this on a budget of a few thousand dollars. That's now a few hundred dollars. And fully autonomous operation is not far in the future: it's just not that hard.
So the reason no one has done anything about this is that hardly anyone has been paying attention, and those of us who have believe that drone technology is worth the price of the risk posed by machines like this. There was simply no way to not get to this point without cutting off development of half-a-dozen technologies that are too important for too many things to ignore, not even counting the economic benefits of drones themselves.