Did somebody (such as police) also contacted Toyota , to open the tracing system of the car to check where the blue Toyota Tacoma with a California license plate 24478S1 could be ?
They don't do that with voluntarily missing people.
Adults who want to go off by themselves and be out of touch cannot be spied on by LE. Something has to trigger such a move (and a court order is needed). Although, if family members (of JRF) could contact Toyota and had enough information about the car and JRF has their name on his account, then that family member could get the info.
I doubt that JRF has anyone else's name on his account though (most people don't, unless it's a co-owner of the car).
Ground searches over such a vast area cannot be organized, especially in the desert but even if elsewhere. Some location must anchor the search - and in this case, that would be the location of the truck. I'm guessing that all rangers on public land know about this case and are dutifully keeping an eye out - but there are tons and tons of dirt/sand roads throughout the region, some with dispersed camping. Since there's virtually no media coverage, very few people would be looking for that truck.
In the case of Barbara Thomas (who was found a couple of miles away from where she disappeared in the Mojave Preserve), the searchers searched 1 square mile from the last point where she was seen, and then about half a mile down the road where her RV was parked (they didn't even go off the road). No SARS crew wants their members to get lost. So the search lasted a few hours, had 2 sniffer dogs (who couldn't find a trail) and then it was over. I contacted one of the members with a tip (via then-Twitter) and was told that SARS volunteers will be kicked off the team if they take individual actions to search that are not formally approved (and accompanied by) Sheriff's personnel. This was in San Bernardino County.
Someday, the truck should be found - and then the search can begin.
As to Occam's razor, my mind goes to wilderness misadventure when two people are known to be driving around in the desert. Neither person in this couple decided to leave word with family or friends about their travel plans (apparently). Which means, to me, they were not mentally prepared for a long hike or expedition. Going off the road into a ravine comes to mind.
I think all of us are troubled by JRF's ping in Julian - and his disappearance thereafter, as it seemed he was driving south and Fang's phone had stopped contacting cell towers...3 days before? 2 days? Can't recall.
IMO