Yes, perhaps "avoidable" isn't the right word. You're right that this is entirely about evaluating and weighing the level of benefit against the level of inconv

Yes, perhaps "avoidable" isn't the right word. You're right that this is entirely about evaluating and weighing the level of benefit against the level of inconvenience. It's rude to run through a crowded theater because you're in a hurry to leave. It isn't rude if you're making an emergency run to the bathroom. We all very clearly and intuitively understand this distinction. By the way, the whole point of politeness is that it requires these kinds of judgements and therefore resists strict rule-making. Ideally, we wouldn't need to make a rule about dogs on planes, because nervous flyers would feel individual shame at the idea of inconveniencing other people for their own personal benefit. I couldn't possibly bring my dog on a plane, not because of any rule, but because I'd be embarrassed and extremely uncomfortable about my own behavior. It would ultimately result in a worse experience for me, for those reasons. I'd be a self-conscious wreck.