As the partner of a senior CC member and someone who travels a lot with them I can honestly say I have never experienced 'landing drinks'.
Years ago maybe (my father was a 707 captain) the practice was common.
My partner allows at least 24hrs between any drink and working. Thus, a backtoback N. Atlantic trip involves no alcohol at all.
My own experience of being downroute many times is that the vast majority of people abide by this.
One thing that would put the publics mind at rest over this is random drink and drug test; something already in place in other industries and not at all uncommon with airlines.
Everyone would then know quite clearly where they stand, no ifs buts or maybe's..