Exactly. It would have been far easier for the perpetrator to simply kill her, as opposed to taking the immense risk and hassle of kidnapping her.
I'm not an expert on child or teen psychology, but Elizabeth Smart was kidnapped without a struggle. She was led out of the house without waking anyone, but her sister sleeping in the same room.
I think self-preservation would kick in. I'm not sure if someone shot and killed my family, I'd be in any position to resist. I may go with the perp without a fight in hopes to see another day.