Originally Posted by
gerald_g
Left arm is needed because a motorcyclist can't release the throttle to signal with right arm.
Any motorcyclist I've ever seen that didn't have turn signals solved that problem by not bothering to signal with their arm.
And since most car drivers can't be bothered to use their turn signals in the first place, I don't expect them to suddenly start using their left arm to signal turns if they become aware that their turn signals don't work...