>, because where as a motorcyclists vision is significantly impaired from the helmet...

This is incorrect. My vision on the bike is not impaired by my helmet. My field of view in a car is more restricted -- and critically in SMIDSY situations, the peripheral field is obstructed by the pillars holding the roof up. SMIDSYs happen when the car fails to give way to the bike; usually this is due to the fact that bikes are small visual targets or unexpected ones. We may mitigate these problems by raising the visual salience of the bike, but we solve them by designing intersections such that they can't happen.