Stating a belief that it is or should be beyond the right of government to protect a person from his own personal choices is very libertarian and (classically) liberal. Plato would be proud. It's also separate and apart from the fact of long settled law that government can do exactly that. Whether it be setting speed limits, banning illicit narcotics, passing seatbelt requirements, proscribing many other types of self harmful behavior or passing helmet laws. Whether we like it or not there is no question in this country of whether or not government can legislate in ways to "protect" people from their own choices.
I am hardly liberal (not that there is anything wrong with that

). Personal "choices" -as you put it - is different from personal safety. In your listed examples, only a seatbelt law applies to my point. Excessive speed is a public safety issue as a person's ability to operate a vehicle at that speed may can certainly put the public in harm's way. For narcotics, it is only the sale and possession that is illegal, having them in your system in the privacy of your own dwelling is not. I agree that the government does pass these laws, I just fundamentaly disagree that they have the proper authority to.
It's also separate and apart from the fact of long settled law that government can do exactly that.
It is neither separate nor apart from, and is anything but "long settled law".
In
American Motorcycle Association v. Davids, 158 N.W.2d 72, decided July 23, 1968, the three judges constituting Division 2 of the Court of Appeals of Michigan held the statute unconstitutional, reversing a contrary holding by the trial judge. Division 2 of the Court of Appeals concluded: "The precedential consequences of 'stretching our imagination' to find a relationship to the public health, safety and welfare, require the invalidation of this statute."
At least one Court of Appeals was correct in their judgement. Most are not. In order to invoke legislation outside of "public safety", States must use the "Police Power" within the State. This again (my opinion) is abuse of power in as much as police power should only be invoked in order to provide for the safety of the general public - meaning - innocent people become harmed in riots, etc. However, other States have used "public safety" in order to uphold helmet laws:
From
State of North Carolina. v. Kenneth Calvin Anderson CITE AS: 275 N.C. 168, 166 S.E.2D 49
:
"The Supreme Court of Rhode Island, in
State ex rel. Colvin v. Lombardi, 241 A.2d 625, decided May 8, 1968, passed on the constitutionality of the Rhode Island helmet statute. The Court said: " 'However, it is our unqualified judgment that the purpose sought to be achieved by requiring cyclists to wear protective headgear clearly qualified as a proper subject for legislation.
(T)he requirement of protective headgear for the exposed operator bears a reasonable relationship to highway safety generally. It does not tax the intellect to comprehend that loose stones on the highway kicked up by passing vehicles, or fallen objects such as windblown tree branches . . . against which the operator of a closed vehicle has some protection, could so affect the operator of a motorcycle as to cause him momentarily to lose control and thus become a menace to other vehicles on the highway.' "
Pay special attention to the "menace to other vehicles". That is what gives authority for passage under public safety laws. Whether it is a valid and reasonable finding is pretty questionable - I mean - those same occurrances on the torso, legs, feet, hands, arms - not just the head - would have the same effect. Why not require full body armor?
Also of note is the fact that Rhode Island in
State ex rel. Colvin v. Lombardi, 241 A.2d 625, "passed" on whether the statute was constitutional - meaning - we won't form a decision on that issue. The State of Michigan clearly found it to be unconstitutional and instead of Rhode Island addressing whether or not Michigan found correctly, they just decided not to address it. In essence their decision was ... "it is our unqualified judgment that the purpose sought to be achieved by requiring cyclists to wear protective headgear clearly qualified as a proper subject for legislation - we don't care if it is constituional or not"
Nice ... huh?