In nearly 40 years of flying I can only recall a couple of instances of being photographed in the cabin.
That said if an aircrew colleague walked into head office and started taking various passers by on their camera I think that might cause comment.
So maybe context, locality and use to which any image is put should define the boundaries. In a closed environment like an aircraft cabin politeness should be first and the shutter second.
Hark! Is that Henri Cartier-Bresson getting up to full rpm?
SGC