And yet here I am having to needlessly explain that that's only necessary when the chance of those externalities is severe enough to warrant this consideration.
As I've shown in this thread, that's not the case, and the dangers you're all supposedly worried about aren't actually real dangers.
But you've all confused shouldn't with can't (whether intentionally or otherwise), and your moral superiority complexes over people having the audacity to make stupid decisions won't let you acknowledge that.
Absolutely - we make decisions every day on the assumption that the people around us are making smart decisions as well, and that's not always the case, and other people sometimes suffer negative outcomes as a result of those stupid, but legal, decisions.
And when you've come to the point where you're having to fabricate the kind of incredibly specific scenario you're proposing to get even a hypothetical externality, you're probably dealing with a situation that should be left to individual choice.
I'd also be completely fine with immunity to charges of manslaughter against anyone hit while not wearing a seatbelt, or something of that nature (and significantly higher insurance rates too, of course).
I understand the counter-argument that you'd probably suffer increased trauma in this incredibly specific scenario that you've concocted, but death is a fact of life, and with how far removed we are in this scenario from the likelihood of direct negative outcomes, I still feel that the agency to make one's own choices far outweighs any hypothetical marginal social good of legislation.