The question seems to be, how do you effectively assess a persons ability to fly a passenger aircraft reliably and safely?
People develop their character and become 'professional' through training and experience.
When they become truly professional they understand that once in the driving seat (so to speak) any personal or outside influences are a big no-no and are not a factor in the performance of their work.
Training in any industry should not simply be focused on teaching a skill but also in building character. That means a tough (not to say ruthless) training schedule designed to weed out those who don't have what it takes at an early stage.
Does the present day airline industry have such a training schedule?