I briefly studied law in the Netherlands and it was used as an example. Our lecturer told us that if "A person on a bike would jump out of an airplane on a bike, land with a parachute on a highway and get hit by a car, just maybe would the car have a case." The reasons for this are varied. Cars are insured, bikes are not. But most importantly, in basically all traffic situations with cars and bikes the car introduces the danger and should thus bear the responsibility of any accidents.

If I go out in public swinging a katana, and someone walks in to it. I'm still the person swinging a katana in public. Driving around in 1.5 metric tonnes of steel and glass comes with certain responsibilities.