That is (unfortunately) not entirely true. If they have reason to suspect there is an immediate risk of injury or death, they can locate the phone (assuming it'

That is (unfortunately) not entirely true. If they have reason to suspect there is an immediate risk of injury or death, they can locate the phone (assuming it's on) with a high degree of accuracy (at the very least, cell tower triangulation, if not GPS activation). We had a situation a few years ago where a couple kids had skipped school and gone joyriding in a quarry. Their parents contacted the police, who contacted the cell phone company, and the cell company gave them a reasonably accurate fix (I assume this was voluntary on the part of the phone company, given how quickly it happened).