"I don't know if we have the terminology to talk about this kind of failure mode."

We actually have and is called RISK.

RISK = Probability * Damage.

Applied to the seatbelt event we have a death level damage and a high probability of happening given recent studies, so using a simple belt could easily save you from deadly accidents.

Applied to any unrealistic scenario we have insane level damages but also an incredibly low probability (near 0) so RISK = ~0%