This accident could have been just bad luck for JW, plain and simple.
I live in Ridgecrest, CA. I am familiar with CA-178 - it's one of two routes to Bakersfield.
The route east from the mouth of the canyon is very narrow, very winding, and has only sporadic guardrails. I can't find current accident statistics, but I'd wager that not a week goes by without some kind of motor vehicle accident, many of them fatal. It gets snow in the winter, rain in the spring and fall, rockslides, and lots of traffic to Kernville, Lake Isabella, and other scenic places.
Wikipedia,
California State Route 178 - Wikipedia: "Turning northeast <from Bakersfield on CA-178>, the route continues to the mouth of Kern Canyon (which is also the northeastern city limits of Bakersfield). For the next approximately 8 miles, the route is a narrow 2-lane road (average width of 18 ft. to 24 ft.), as it ascends the lower Sierra Nevada. Average speed is 35 mph, with sharp turns and steep drop offs." This would be the part where JW went off the road.
Additionally,
California Highways (www.cahighways.org): Routes 177 through 184 - and this is an older reference, possibly 2013:
"The canyon segment of Route 178 scores a unheard of 257 on the state's safety index; this means that the canyon portion of Route 178 gets 257% more accidents than would be expected on a mythical state highway with similar average daily traffic."
Also, from the same website: "Currently there are guardrails installed sporadically along Route 178 in the canyon. When Caltrans was asked whether additional guardrails could be installed, the response was that many locations in the canyon only have one or two feet of shoulder, and Caltrans needs more than that to properly and safely install guardrailing."