I try to follow as many California desert stories as I can. Most desert disappearances that I'm aware of (I've been watching for about 10 years) end up being foul play. There was a rather famous case (which involved a woman from AZ, not far from where Barb lived) in which there was a voluntary disappearance. The woman was walking in the Mojave Preserve, IIRC, having had some kind of falling out with her traveling partner. She got into a car with strangers, went to Vegas, partied for a few days, and then was dropped off in Laughlin, where she contacted family.
I may be misremembering a couple of details. Anyway, I've often thought that RT's belief that the same happened to Barbara (at least, his initial story about what happened) paralleled that woman's story and made his own story more plausible. RT and Barbara were living in the area at the time. RT frequently went to Laughlin (per VI).
At any rate, there are some never found (and obviously, could be a lot we don't know about). But I consider the entire area around the Mojave Preserve to be a higher crime area. I've witnessed a robbery and two assaults in Barstow (over the last 25 years). There are bodies found out there, victims of foul play either in the desert or elsewhere, so many abandoned car/missing person cases...the desert is a scary place for many reasons.
That being said, I wouldn't have thought too much about my personal safety on a brief stop on Kelbaker Road, there are a couple of businesses nearby, it's not *that* isolated.
I too think we can rule out deliberate disappearance. <modsnip>