Flight Attendants who have flown for more than 3 months have all experienced first hand the endless amount of trouble caused by some clever passenger surreptitiously drinking their own booze on-board.
Confirmed by an incident I witnessed which occurred on a flight from AMS - DXB with KL.
One pax was caught red handed drinking his airport purchased duty free whisky (nearly a full bottle) and who was obviously 'well refreshed'. He became abusive and agitated when a member of the cabin crew remonstrated with him to the point he got out of his seat and I thought there was going to be a serious confrontation. This guy was well built and I feared for the cabin crew who were attempting to deal with him.
Fortunately, the two members of the CC were assisted by another colleague who did not mess about. He was able to restrain the unruly pax (in a crude but effective manner I might add) and his remaining alcohol was confiscated. The crew did a great job, however, people should not have to be threatened or abused while doing their work - policies and procedures are there to reduce the risks of such occurrences.
The drinking of alcohol on an aircraft will always be a contentious issue, and for the majority, there is no problem and is an enjoyable part of the flying experience and I sympathise with the staff that have to enforce their respective employer’s policy to the people who believe they are exempt from complying.
It is a difficult one, but rules, policies and regulations are there for a reason - if one does not like a particular airlines policy, then use another carrier - if that option does not exist, then it is a case of well.......Tough!
Oh, by the way, on landing at DXB, the drunken passenger who managed to sleep for the rest of the flight had a rude awakening when two members of the Dubai Constabulary carted the miscreant off to the local nick.