each of us is just as vulnerable to being killed.
I disagree with this part. The casualty figures for each category of road user per billion miles travelled show that pedestrians, cyclists and motorcyclist are far more likely to be killed or injured than any other.
People in motor cars have sophisticated and effective protection systems that insulate them from harm to such a degree that, as drivers, they lose all perspective of the harm to which those outwith those cars are exposed.
I would also suggest that this insulation from harm engenders the bullying attitude so often seen in encounters between drivers and vulnerable road users. And by that I'm not talking only about collisions but the general interactions on the road. Drivers will often intimidate pedestrians at crossings by creeping forward or revving their engine, even though the pedestrian still has priority; fail to wait behind parked vehicles on their side when a cyclist is coming the other way; squeeze past a cyclist at a pinch point etc.
They flex their muscles this way through a sense of greater entitlement and importance and in the knowledge that, in the event of a collision, they are least likely to be injured.
So, while everyone has responsibility for road safety, those who bring the greater risk of harm bear greater responsibility.