I think drivers should be more aware and conscious that they are piloting a 2 ton or so vehicle. We all drive our vehicles next to everything from scooters to double tractor trailers. I have people turn in front of me in my car or motorcycle on a fairly regular basis because they are poorly trained and misjudge my speed.
The driver sounds like they were fairly young and inexperienced. I drive slowly around that area because there are so many cyclists and I take my time passing them. Their safety and peace of mind is worthy of a few moments of my time.
As someone who both bikes and drives, I think bikers could also be a lot more aware and conscious that they are piloting a vehicle with no protection around 2 ton or so vehicles. The burden of safety should be split equally regardless of whose vehicle is heavier.
While I've been lucky enough not to see a full-on crash, I've seen a few situations where bikers were almost in very serious accidents here in San Diego where I felt the biker would have totally been at fault if the collision wasn't luckily averted.
When it comes to personal decisions, 100% of the responsibility lies with me. When I'm driving, 100% of the responsibility to avoid hitting a bicyclist lies with me; when I'm biking, 100% of the responsibility to avoid being hit by a car lies with me. The idea being that everyone else on the road is absolutely crazy, so my responsibility is just to be prepared for their insanity and act accordingly. I think this philosophy increases my likelihood of survival.
On the other hand, when it comes to cultural and (to some extent) legal ideas about "responsibility," I do think that the idea that "with great power comes great responsibility" (thanks, Spiderman) is a pretty decent heuristic. Lots of people have no concept of their own vulnerability, and lots of people have no sense of their own power to do harm, but one will hurt me and the other hurts others. Plus, and maybe for that reason, I think it's a lot more difficult to forget vulnerability (it's obvious every time a car flies past 3 feet away) than it is to forget power--passing a bicyclist with a couple feet of room just doesn't feel scary to lots of drivers.
There is one fairly big difference. People who drive cars have to be licensed, with the legal liability that goes with that, and the potential to completely lose that privilege, which is a constraint.
When I hear people here saying that they can go right up to the speed limit on a bike in poor visibility without any concerns, it makes me think cyclists should go through the same process.
I'm a cyclist, and I rode that same stretch, and my bike computer told me I never went above 25 mph. Because I value my life.
For my self preservation I don't bike there. I don't want to be the statistic, and there are so many other places to bicycle without dangerous car traffic. Driving in general works out because the people around us can usually compensate for the mistakes that we'll invariably make, and thus avoid (or mitigate) an accident. This is harder for a bicyclist --- a bicyclist can't accelerate away, handle a swipe, recover from a collision, and is harder to see.
Having biked there (once) it's simple. I apply the brakes on downhills. If you're riding on a bike trail with excellent visibility, you can go flat out. If you're riding on a 2 lane road with no bike lane, poor visibility, and no shoulder, you slow down.
When there are speeding vehicles and no shoulder or bike line, you are usually safer to speed up yourself. If the speed limit is 40, they'll be cars going around the curves at 50. Just after a curve is the most dangerous spot for getting hit from behind, and you really want to get out of there.
This might be true if the speed was not gravity-assisted and at the edge of the athlete's performance. Braddley wiggins can take it 35mph and ride with traffic on the flats. He can accelerate (up and down) on his own volition. 40 miles per hour is more speed than most can handle, in terms of decelleration, on 20-23c slicks high pressure tires with minimal surface area, to a terminal speed of zero. While modern brakes are good, they are not that good. Usually the solution is to swerve (avoidance), but in this case it appears there are no shoulders, and consequences off the Tarmac. It doesn't take 170+ IQ to figure out you need to respect your limits in the terrain--it has objective dangers. As an avid cyclist (and someone with experience in dangerous riding conditions) the arrogance of some others I see (both on the roads in in these comments) is surprising. It seems like there is some territorial issues at play. Regardless, one needs to respect objective hazard and their absolute skill levels as those risks rise.
The driver sounds like they were fairly young and inexperienced. I drive slowly around that area because there are so many cyclists and I take my time passing them. Their safety and peace of mind is worthy of a few moments of my time.