> Then, while you still won't be able to stop assassinations and such, just like you can't stop them now anyway, you can at least know who did it
Even if you get criminals to comply as far as only operating drones with proper IDs, so that you can trace the legal purchase history of a drone, that doesn't mean you know who used the drone. Drones and their supporting control equipment can be stolen (and the owners prevented by force from reporting the theft) and people willing to commit assassination by drone certainly wouldn't be unwilling to commit theft, kidnapping, and/or murder of drone owners to acheive that.
Even if you get criminals to comply as far as only operating drones with proper IDs, so that you can trace the legal purchase history of a drone, that doesn't mean you know who used the drone. Drones and their supporting control equipment can be stolen (and the owners prevented by force from reporting the theft) and people willing to commit assassination by drone certainly wouldn't be unwilling to commit theft, kidnapping, and/or murder of drone owners to acheive that.