"We'll leave this issue of reasonableness aside, for now. But the police do not have a responsibility to investigate. They cannot be held criminally liable or sued civilly for failing to do so."
We will definitely have to agree to disagree on this one. A family reports that a young woman vanishes four days before a lavish planned wedding, and the police NOT be expected to mount an investigation and search? And them risk her being found dead, and they not done enough? I can't see it in this day and age. And any reasonable adult would know such a search would be made.
"Jennifer Wilbanks did not ask anybody to look for her. She didn't leave a note, or call the police, or toss her apartment, or do anything deliberate to make it look like she had been kidnapped. How can she be held responsible for the actions of others?"
The request to be looked for is assumed, and quite rightly. "Please find the people who have kidnapped me and have me captive". The situation is akin to the rescue efforts mounted for a stranded mountain climber.
You're talking about expectations. I was talking about legal liability. The Police would simply not be liable if they "failed" to start an investigation. As it turns out, in this case, if they had followed procedure, none of this would have happened.
Frankly, to my mind the fact that this woman was to be married in a few days time with 600 guests and 14 bridesmaids makes her much more rather than less likely to flee. For the Police to look at that fact pattern and immediately conclude "kidnapping" seems like a serious misjudgement. If you ask me (and I know that nobody did), Daddy pulled strings and twisted arms to make this into a huge brough-ha-ha. If you are looking for somebody to blame, blame him.