I think people don't watch the news more than we know. A young woman about my age was dismembered in a shocking and horrific way and the case unraveled in a very dramatic way there was fear because the person wasn't caught right away and it got overwhelming news coverage and I cannot tell you how many of my friends had no idea even though it happened in our town. I would bring it up and they would be like huh? What? Someone died? What are you talking about?
More people don't watch the news or necessarily discuss the news than one would realize. I definitely believe the neighbors who claim they had no idea a girl was missing near them.
I do think, overall, that it probably was left after dark. I just don't assume literally everyone knew right away that she was missing or that a backpack should invoke immediately calling LE. Him emailing a community listserv first seems reasonable to me.
Not saying what he did was unreasonable at all. Just stating that someone really has to not want to know what's going on in the world to completely miss all news/radio broadcasts for a full 12 hours and then miss it for another 6 when he left his house.
An example a 12 year old just walked out of school a few weeks ago. It was on the midday new's, it was on facebook, they were talking about it on local AM radio, they had news announcments on local FM radio. If you were in range of a TV, computer or radio people in our town new about it.