This has to be one of the stupidest ideas I've ever heard in my life. Not because it doesn't possibly have some noble intent behind it, but - if for no other reason - because it's going to be bloody impossible to enforce. When any hobbyist can easily build a drone/UAV without much in the way of special skills or equipment, how in the hell do they ever expect they'll get everybody to register them?
You can build a bicycle much more easily than a drone and many counties and some countries require people to register their bicycles.