This is the reason why an autonomous car should have radar/lidar. With those sensors such a scenario would be extremely easy to detect.
Now of course he did do it "too late" to avoid any collision, but at what point are we expecting an attentive human driver to realise that their self-driving care has decided not to stop at an oncoming train and make the split-second decision to intervene?
If we expect drivers to mistrust their allegedly self-driving vehicles to the point that they must be ready to anticipate the car failing to react to an oncoming obstacle and immediately intervene, then this is not self-driving technology — it is human driving with extra steps.
Well, it is not self driving. Anyone who uses FSD Beta is beta-testing it and should be paying the same amount of attention as if they were driving themselves. It is human driving with extra steps.
(I use Tesla autopilot, don't have FSD.)
Putting aside that the initials "FSD" stand for "Full Self-Driving", the level of attention of ordinary human driving is not enough. If that is the case, FSD Beta is accidents waiting to happen and should be removed from public roads.
Human driving goes beyond the factual realisation that there is a train crossing the road and the driver reasoning that they must push the brake. Rather, it is the driver having a constant feedback loop of information followed by intuitive reactions as to the action to take. Case in point, the cliché of having driven all they way from home to work and vice-versa and realising that one cannot remember the journey, even though the driver paid full attention to all rules and reacted appropriately to each obstacle. An attentive driver may even brake their vehicle when an object has flown into vision before having actually processed what the object was.
Compare that to the type of attention that would be necessary for "FSD Beta". The speed at which the car is travelling is disconnected from any immediate feedback loop in the driver's nervous system. The driver sees an obstacle in the road, one of many over the past few weeks which required no intervention given that the car reacted appropriately. Here is another obstacle. Has the car seen this one? If not, will the car see it soon? Will it react appropriately in time? Should the driver intervene now? That requires much greater attention and decision making than the intuitive process of human driving, all the more so considering that the majority of the time the occupant of the driver's seat in the "FSD" car is becoming accustomed that there's no need to intervene.
Respectfully, that's the point. People have been stating this clearly and unambiguously for years. People are not designed for that kind of split-second monitoring for hours on-end.
"oh look, a railroad crossing with a train crossing"
"we're getting close to the crossing, surely he noticed the train"
"why aren't we slowing down? oh crap he falls asleep at the wheel"
*grab the wheel and steer off the road*
As long as self driving cars require constant supervision, I think this kind of accidents will keep happening. Drivers will have reduced reaction time when they're not actively driving the car.
Radar would, but radar is also a bit crap - in particular angular resolution is very very poor.
The usual diameter of fog droplets is in the micrometer range, but is highly variable.
So microwave/milimeterwave lidar could theoretically work.
That isn't what you want, but it's a limit of current commercially viable radar technology.