I’m a bit amazed that everybody has come to the conclusion the op bears no culpability in this situation.
The damage as explained is not what one would expect from a person “moving forward” (at what speed) being impacted by a car that was backing from a parking space.
Now saying it is op’s fault but come on; the damage shattered the window, caused the side view mirror to fly into the op’s car and the damage continue the length of the op’s car.
Just how fast do you have to be moving to not be able to stop before you continue for another 10 feet or so after a car backs into you?
Maybe questions like;
Did the other drivers insurance company explain why they feel you are 10% culpable?
Should be asked before total condemnation of the insurance industry in whole.