That hurdle already exists in the UK in the form of Remotely Piloted Aircraft Systems (RPAS) certification (AKA Remote Pilot Competence), which requires passing

That hurdle already exists in the UK in the form of Remotely Piloted Aircraft Systems (RPAS) certification (AKA Remote Pilot Competence), which requires passing a theory test, a practical test on the specific equipment that will be flown commercially, as well as development of an Operations Manual that is reviewed as part of the certification process. Commercial insurance is also required. What the proposed registration process is attempting to address is the misuse of hobby multi-rotors. The difficulty the it faces is in retrofitting it to an existing market. Those who are too dumb or ignorant to fly legally (and since multi-rotors have become too easy to acquire and fly, there are many), are going to be the ones who also fail to register. Requiring registration prior to purchase is one possibility, and having mandatory geo-fencing on all new systems seems like the only way to gradually introduce a system that restricts use in controlled airspace, and over populated areas, but it will never be able to account for every scenario in which people insist on breaking the law, invading privacy or putting others at risk of injury.