And yet, by and large, those same people fail to ask that same question in respect of grown-up persons and seem to have little hesitation in posting pictures of /them/ to social media where the pictures will also "never" go away.

Seems to me it would only be respectful to /ask first/ whether the people in some party snap are all OK with having their image posted somewhere, tagged and identified and sucked into somebody's gigantic social graph database, but this is clearly not the norm.

Yup, I'm very conscious of this. I wrote a longer comment in regards to this elsewhere in this thread.