"Luckily there remains some scope for decision-making based on personal abilities and experiences "
These days no-one is going to allow anyone near the cockpit if there is the slightest doubt that they are intoxicated (well at least outside the Russian Federation). If there is a medical reason why they appear over the limit then it may still impair their performance. If they are not impaired (for whatever reason) they have the chance to explain/ be tested but no-one is put at risk.