Because of the drugs, one's ability to judge is compromised and hence even the countries that allow alcohol and drugs, ban the use for the drivers and workers.
What I learnt about the truck drivers in Pakistan is that they driver for extremely long hours and they are forced by the tough deadline given to them by the owners. Hence they resort to drugs to keep the stress control but anything artificial makes you stress free for sometime results in permanent damage.
It is like coffee. During my MS... I overestimated by abilities since being a good student and having good grades, I started another MS in parallel before finishing the first one as I got a scholarship that waved off my the university fee. However I have to work really hard and double the time on two very different lines... aerospace engineering and IT so I started using more and more coffee day and night..7-8 cups of pure black coffee without sugar & milk. But that started to affect my sleep adversely and it was reduced to only below 4 hrs at its worst... I could not sleep on time though I managed to pass both the degrees but it took me more than 6 months to get back to my normal sleep after reducing coffee to just one or two cups per day..
