Well, the enforcement mechanism for manners.

Yes, a shared understanding of the rules. Common context. Culture.

There are in fact expectations of your behavior and that is not a bad thing, despite western popular culture attempting to tell us otherwise.

In an industrial society, too many rule followers results in people being reduced to cattle. We need a subset of our society to be ungovernable in order to stave off tyranny, because historically, smart people aren't trying or succeeding at that. As another commenter in this thread stated, though under different context, our bodies wouldn't make the venom if we didn't need it to survive.

eating a smelly pizza in a cinema doesn't make you one of the Tolpuddle Martyrs

End stage capitalism is itself a result of shamelessness.

maybe they just mean consideration for others