Yet you provide neither specificity nor case law to support your position. Hand-waving, "It's unconstitutional!" doesn't actually make an argument. It has about as much weight as "But I said so!"
If you want to wade through case law on helmet laws be prepared to be confused.
I waded through the case law. It was not very confusing.
Only two states found the laws violated their own constitutions. No other states have found that. And only one state has had the challenge make it to SCOTUS.
and?
You said: If you want to wade through case law, it's confusing.
I said: No, it isn't.
You said: Why did so many states stop?
I said: Retraction of the laws. Only two states lost the laws to court cases.
In other words, since you seem unable to extrapolate, the overwhelming likelihood is that the laws are Constitutional by both federal and state documents.