I think a lot of proficiency test should follow the process used in full scale.
1) System comprehension. You will never be in command of an aircraft unless and until you understand what makes it work. The applicant should be able to describe the systems used in their aircraft and how each associates with others to make it all work. Batteries, chargers, GPS, accelerometers, baro altimeter, flight controller functionality, frequencies used and what each is applicable to, the reason for calibrations, aircraft and system inspections, description of lost link/lost comms functionality.
2) Decision making. How someone deals with various situations is predictive of how they will operate when they are by themselves. Just like full scale, provide the applicant with a flight location and tasks where they will have to describe what they will or won't be able to do, how they would conduct the flight, how they would mitigate risks, how many batteries would be necessary, battery depletion level and when a battery should be changed out, whether or not the flight could be flown at all.
I well remember being provided a destination for a 50+ mile cross country to plan out and present to the examiner. It was technically a beautiful VFR day but had towering cumulus clouds for much of the route of flight. High humidity, and temperatures were expected to rise considerably throughout the day. Could we have made the flight? Yes, but we would have been beaten up badly by moderate to severe turbulence for most of the flight. Due to an onshore flow of moist air that was being blown by a light wind up the slopes of nearby mountains the prospect of encountering T-storms during the flight was pretty high. My suggestion to go somewhere else and save that destination for another day demonstrated an understanding of things that affect flight and reasonable decision making.
3) Demonstrate manual control of the aircraft. Anyone can fly an automated aircraft. Truth is, they really aren't flying one at all, they are simply telling it the direction they want it to go by pushing on a stick. The aircraft is flying itself when in an automated or semi autonomous state and it doesn't need anyone at the sticks to fly well. Make applicants fly in modes like Atti, Non GPS Angle, or Stabilized where GPS provides no directional assist and the aircraft drifts with the wind if the operator fails to allow for wind drift. Demonstrate manual take off and landing, preferable with some level of wind present. Observe how far they elect to fly out to determine if they truly understand what line of sight means.
4) Describe and Demonstrate emergency procedures. If they don't know what to do when chit starts hitting the fan they don't need to be flying. The last thing we need is some guy running around waving his arms around in the air like the kid running out of the forest in Robin Hood, Men in Tights when things start going wrong. People need to know what to do well enough to automatically shift into emergency mode the moment something happens, not fumbling around trying to figure out what to do. Determine if they understand there could be a time the only appropriate action would be one that caused the destruction of their aircraft via an intentional power cut at altitude.
For commercial operators the tasks need to be more demanding, and include additional demonstrations of crew coordination/delegation of tasks, use of VO's, safety briefings, site surveys, descriptions of spectator and crowd control scenarios, effective risk mitigation, use of aeronautical information in mission planning, and accident reporting. It should be demonstrated that a commercial pilot has a far greater understanding of their aircraft and be able to extract maximum performance from the aircraft.
