Maybe it's television, as someone pointed out, maybe it's just that we don't trust people anymore. With good reason - look how much time and effort went into searching for allegedly abducted children that turned out to have been killed, or sold to be killed, by their parents. In those children's names, I think the police and the public have to be at least a little suspicious of the parents during disappearances, especially when it's a "stranger in the middle of the night."
I never thought Jaycee's stepfather was involved. I did think Zahra Baker's stepmother killed her, which the justice system upheld. Shaniya Davis' mother - not a doubt. This story just seems too bad-mystery-novel-ish for my taste, although it's plausible. I haven't seen any video footage of the parents, so I hope I'm wrong.