> That doesn't mean we paralyze ourselves with inaction or always prioritize marginal improvements to safety (even others' safety) over all other concerns.
Frankly I don't care if a (private) road owner wants to require specific safety equipment on the vehicles allowed on their roads. Their property, their rules. Other potential users of the roads can then decide whether they're willing to accept the residual risk. But that argument depends heavily on those who are being excluded (for lack of required safety equipment or low risk tolerance) not being forced to pay for those roads' construction and upkeep. It doesn't work for a government mandating systems to be installed on all vehicles, or for tax-funded roads.
You’re asserting strongly that the changes are marginal. And sure, the efficacy of the mechanism should be considered. But the point remains.
Your individualism is irrelevant.
Mandatory safety features, on the other hand, are a direct example of a negative externality: Those wanting the safety features to be mandatory get what they want while other people bear the cost.