Actually the difference in outcome between a motorcyclists with or without helmet is less different than the difference between an automobile driver wearing a seat belt and one that is not. Basically if your motorcycle is crashed the outcome is going to be bad regardless of helmet status. However, when in a car if you are wearing your seat belt often a person can have minimal or no injury after an accident, a person not wearing a seat belt is very likely to have bad outcome.At least I have the freedom to hop on my Harley and ride without a helmet.
Now wait, IF I have that freedom to ride with increased risk of bodily harm without a helmet then WHY do I need to wear a seat belt or get a ticket?
Automobiles have built in passive restraint systems call air bags. Bikes have none of that.
Answer that smarty pants!
It can also be argued that the difference in the experience of riding a motorcycle is greatly affected by wearing a helmet and the difference in experience between wearing a seat belt or not while driving a car is minimal.