No requirement to wear armor, no requirement to tie themselves to the wagon, etc.
That may seem like an odd distinction, but it is a seminal one.
While it is quite credible that one of the just powers of Government is to protect people from the actions of others by reasonable regulation (with, of course, the consent of the governed), the great shift in government's raison d'etre is to protecting people from their own actions, or, more collectively, protecting society from the actions of the individual which primarily affect the individual.
Of course, the case is often made that doing so is justified, if not out of the wholesome human goodness in our hearts, then by the invasion of the State into the realm of individual responsibility and the subsequent 'cost' to the collective, measured in everything from underfunded health care, to lost productivity, to the 'social costs' of impacts on family units which might stem from injuries.
Early motorcycle safety studies harped on the former, that it was safer to wear a helmet than not.
As far as I have been able to trace the tree of references, (for following studies use earlier ones as references), the earliest study was a study done by the Army in the 40s, which said dispatch riders were safer riding through combat zones with their helmets on.
Subsequent studies referenced that study, then those following referenced the studies which referenced earlier studies, etc, building an inverted pyramid of credibility based on the veracity and completeness of the earlier studies.
Of course, it is relatively easy to take quotes out of context or present conclusions as referenced material (conclusions which may or may not be valid or supported, but once stripped fo their context, live on as peer-reviewed data, to support new ideas which may or may not be valid.
When these studies were being done, the internet was nonexistent or in its infancy, and material had to be scrounged by interlibrary loan, if it could even be found. Often, it could not be, and the tedious process of reading the available references to get the context of the quotes was one all but the most dedicated would forego. (My local librarian hated me in those days, for when I walked in the door it meant more work.)
In the late '70s/early '80s, however, the thrust of the studies was no longer one of who used what voluntarily rather than only when required, nor what was effective in what situation, but of the social cost of acting on individual initiative.
Many of these studies were deeply flawed, logically, mathematically, even to the point of not ascertaining whether those involved in accidents had been using a helmet when the accident occurred. The new thrust had become not the safety of the individual rider from their own actions, nor even 'widows and orphans', but the preservation of the public coffers, which had not been involved so intimately in the fate of the individual until the expansion of the scope of government. This was not a protection against dangerously flawed devices, but a protection of 'society' against the actions of individuals which the studies (albeit with questionable validity) deemed a threat to society, not physically, not even at its moral core and fiber, but at its wallet, a wallet which should have only been involved at individual and charitable consent.
Of course, with (state-required) insurance involved, there was a question of whether public policy could be used to 'stack the deck' in favor of corporate profits, at least as the perception (generated by the studies) would make it seem.
Here, however is the danger, not just to a free state and individual liberty, but to the very integrity of research by which opinions and, ultimately, policy are formed.
Of the studies which I examined, not one noted those detrimental effects on the rider except to summarily dismiss them. Reductions in hearing acuity over specific frequency ranges, reductions in effective peripheral vision, weight and fatigue considerations, heat, fogging/glare effects, increased moments of inertia, both when turning to look for hazards and during involuntary movements when in an accident, fulcrum effects in cervical spinal injury, EMS/first responder removal techniques, and effects on identification of trauma-related cerebrovascular events were pretty much ignored, even though motorcycle riders were acutely aware of some of those effects and becoming aware of others.
Despite public perception, one study did cover orthopaedic injuries, only to find that skull trauma was pretty low on the broken bone list--iirc, ninth or tenth place, ocmpared to other orthopaedic injuries, although that may have changed since, with the change in frontal profile of American vehicles which has occurred since the 1980s.
Many of the junk science tactics used in the flawed studies have resurfaced in other venues, especially in the instance of alleged anthropogenic global warming, and in the instance of tobacco villification, also with enormous assumed profit motives lurking in the wings.
While there has perhaps always been agenda driven research, the past thirty years saw a shift from research done to find answers, to research done to prove a point in order to enact more legislation/regulation, often funded by those seeking to enhance profits or power.
Therein lies the danger of allowing government to creep into issues of personal responsibility by making them public issues, something which is far more pervasive than ever in our society, to the point where alleged Conservatives rail against the liberty of others because it might cost them a dime rather than rail against the pervasive invasiveness of Government which wwould demand the dime be paid.
Does all that mean I have to go out to the Yuke and bring my broadsword back in?