The rule in place is that anyone in a critical position should not be under the influence at work. I think this is fairly commonplace throughout the world.
Here the critical positions are defined wider than in other places, but are not excessive, they include the obvious:- pilots, ATC and some less obvious :- loader, loadmaster, trim clerk, dispatcher. SO simply put, anyone who's error could cause a hazard is required to be sober at work.
It is a general rule with the UAE, so will apply to taxi-drivers, crane operators, nurses, doctors and positions in almost every industry.
It really is nothing to get excited about.