This is a broad and general request for behaviour that is more civilized. Usually, crass behaviour is not deliberate but merely 'unthinking'.
'Respect' is the key word. Civilization is built on respect. If you respect other people then your behaviour will always be civilized.

The request is not so much for the niceties of manner, which can often be forgotten, but for respect for others.

A smoker is not deliberately setting out to upset other people but may have a lack of respect for their preference for a clean atmosphere. Selfishness and lack of respect overlap but are not quite the same thing. You can be selfish and still respect others