In Australia this is not just for minors, you can be fined as an adult for cycling without a helmet which is even more absurd when you look at the lack of cycling infrastructure in Australian cities and the general cultural distain towards cyclists.
In a society it's not fair for your selfish actions to have a negative effect on everyone else.
Are you planning to ban all snowsports? Horse riding? They produce similar or higher levels of injury and disability even with helmets.
>it's not fair for your selfish actions to have a negative effect on everyone else.
If negative externalities are the metric we're evaluating what is and isn't allowed in our society, you're really going to take a pass at cyclist helmets instead of cars? Do you know what the leading cause of child death in Australia is? It's cars