Everyone take a deep breath.

"Fault" and "responsibility" are not synonyms.

Rarely, there are collisions that one party was completely powerless to prevent. The fact that they're rare doesn't make them any less devastating when they do happen. Maybe even more so.

Because of the speed differential between cars and bicis, left-turners are probably high on the list. It's pretty easy for a motorcyclist to avoid getting hit by a left-turner. Not so much for bicis, who may have entered the intersection well before the left-turner even approaches it, and who don't have the power to accelerate fast enough to complete the crossing ahead of the car.

The fact that there is such a thing as a collision that one party was powerless to prevent, doesn't obviate anyone's responsibility for anything. The fact that one party is at fault in a collision, doesn't obviate the fact that the other party usually could still have prevented it. "Usually" is not the same as "always." But it's a long, long way from "never."