Mr Fogg, most airlines have no problem whatsoever with you consuming your own food and drink on the aircraft, but they do have a policy that forbids passengers consuming alcoholic beverages which they have brought on board themselves.
You might not agree with that rule, but that doesn´t change the fact that the rule is in place.
Flight Attendants who do not enforce the company´s rules on board an aircraft, are not doing their job properly.
Not doing your job properly can lead to unpleasantness, disciplinary action and finally the loss of that job.
You call doing your job properly an ´attitude problem´, I call it normal behaviour for anybody who likes their job and the steady (family) income it provides.
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.
When a pax either buys/obtains for free, his alcohol from the FAs, we can try to avoid that person getting drunk. If he drinks his own, that is impossible. And people so keen on alcohol that they drink from their own stash are not usually the ones who will peacefully enjoy a couple of drinks and then snooze the rest of the way.
YOU might, but how representative is one Mr Fogg?
The attitude problem in your post is ascribed to the wrong person(s) Mr Fogg.