Hi, just wanted to say something about parents not reporting their adult children as missing...when I worked in health care many years I met so many people who hadn't seen one of their adult kids for many years, sometimes for decades, and they didn't think of them as missing. They would simply say something along the lines of "I have a son (or daughter) but I don't have any idea where they are, they took off long ago and I haven't heard from them for years".
They didn't think of them as missing, as they were young adults who'd voluntarily left home to wander or seek a new life, they hadn't disappeared under suspicious circumstances. They didn't think of them as endangered or dead, they seemed to take the view that their family member was alive but simply "out there somewhere", especiially if their adult child was known to enjoy a wandering type of life style in the past, for example, traveling to work at/ follow carnivals, or roaming the country with a biker gang, etc.
One personal experience--my brother was one of those who would simply take off sometimes, not contact any one for long periods, then suddenly turn up. When my dad called LE once to try and report him missing during a particularly long stretch without communication, they would hardly talk to my dad, much less take a report-- my dad was simply told, "he's an adult, he can be out of touch if he wants to, for as long as he wants". Their view seemed to be that an adult leaving voluntarily, no suspicious circumstances, wasn't really considered "missing", at least from an LE standpoint.