In North Carolina, there never has been a state law requiring helmets for adults. We've had a 20 year requirement for children under 16 to wear a helmet when riding on public roads and paths. The penalty for non-compliance is a $10 fine to the parents, which is waived if the parent presents proof of helmet acquisition. I have not heard of a single incidence of a parent getting cited, though.
Your article has a quote that presents the logic: “These violations do not have a direct connection to the safety of other individuals on the roads, paths, or sidewalks,”. One could argue that bike helmets are a safety measure; however the key qualifier is "safety of others".
I've always wondered why laws are enacted, but seldom enforced.