Well, you did open up with the bumper stickers. ("Bumper stickers" - do you stick them on your bumpers in America? They are on rear windows here.) And it really has nothing whatsoever to do with the question of "abdication of parental responsibility."

To call it " further evidence of some parents inability to bring up thier kids without outside help" is really total nonsense. It may be a futile thing to do, but asking other drivers to try not to kill your children is not asking for "outside help".
....................

The main "abdication of parental responsibility" I am aware of is where both parents go out to work all God's hours, from an early stage in a child's infancy.   And rather than "abdication" all too often this is imposed on them by a culture and governments that think that the only useful work is waged work, and that looking after children should either be something cobbled together in odd bits of spare time ("quality time"), or needs to be professionalised and rigidly structured.