But you have missed the vital point that the CAA has to approve the logging of Co-pilot time. It is not a right it has to be applied for and hoops jumped through.
The fishery's F406's are a perfect example. One contractor was authorised to allow multi crew time to be logged the previous one wasn't.
Same in the Channel islands on the Tri-lander yes the none auto-pilot machines have 2 crew on board but only the PIC gets to log anything.