The reason why they are getting their knickers in a twist is because they object to anyone telling them what to do.
The fact they have no choice in the matter and it may lead to a criminal record if they refuse is just plain infuriating.
And it should never be "because I am telling you to" although I will admit you more than likely you all have examples of that happening.
If you do see poor handling of pax on a UK flight please report it to.
CHIRP
And they will investigate. And its a top level enquiry which goes in a post holder level ie the person that is responsible to the authority's.
Swear even once at any of the crew or act in an aggressive manner and your off end of story, if it happens in the air you will be met by the police.