A mandate to have health insurance is orders of magnitude more impactful on the unwilling than a mandate to wear a seatbelt. But because of some commonality in the principle behind both mandates, you believe a person must accept the latter if they accept the former, to be morally consistent.
>>Hence back to the earlier point, people aren’t anti-libertarian but rather find much of what is espoused in the name of libertarianism is too absurd to take seriously.
What I encountered when denouncing mandates that turned unvaccinated people into second class citizens is people using our society's acceptance of sanitary permits for restaurants as justification for such mandates. It is a rejection, on principle, of the right to one's own person, property and liberty. For that reason, I conclude anti-libertarianism animates laws that violate the right to private property, bodily autonomy, and personal freedom, whether that be mandatory minimum restaurant safety standards, the Income Tax Act, vaccine mandates or lockdowns.
>>Seat belts and 3 months of Shanghai style quarantines are way different.
Of course they're way different. But the former opens the door to the latter, because there is no hard principle to prevent the latter when you accept the principle that justifies the former. That is how Canada ended up confining 150,000 elderly people in their room for over a year. There was no principled reason not to confine innocent people for the greater good, so once the cost-benefit analysis determined it was the correct policy, the restriction was imposed.
You only oppose "3 months of Shanghai style quarantines" because you view the restrictions as being disproportionate to the public benefit they produce. Not because you oppose restrictions limiting personal autonomy on principle.