May I put in a word for persuasion and tolerance here? Most posters have avoided thumping the table and demanding that 'something be done,' but one or two have overstepped the mark.
If you can't persuade someone to use a helmet, don't take refuge in seeking to 'mandate' it. Given public attitudes towards us, no helicopter pilot should ever use the words ban, prevent, mandate, force, ground, or oughterbealaw without long and careful consideration.