The simple way to avoid drunks on airlines is for airports to stop selling alcohol!
The owners of airports are not airlines, so they maximise any and all opportunities. How else do you explain being able to buy alcohol when you are waiting for a plane.
People get bored and / or nervous waiting for a flight, so they drink, often to excess, and the problems become the airlines’ – not the airports, because the trouble starts when the drunken passenger is confined in a small pressurised tube which exacerbates his or her boredom, feeling of restriction, and the effect of alcohol is increased – a recipe for trouble.
So, let the airlines lobby the airlines to stop selling alcohol, and the problem will disappear overnight.
Of course, it won’t happen – but that is the answer.