A 747 isn't a spacecraft travelling at supersonic speeds, so it's not really the type of craft relevant to the discussion. Cars, buses and boats also aren't loaded with self-destruct mechanisms for obvious reasons.
Obvious enough that I had assumed craft = aircraft as well since you can "take the keys out" of ground/water vehicles. I was challenging the thought that every aircraft needs self destruct, as I suspect it's a minority. If as you say supersonic capability is the threat threshold, fighter jets/rockets would have them but a C-5 Galaxy and Blackhawk might not (I don't know, I'm speculating).
In this context, I meant craft = spacecraft. Our current space launch technology relies on extremely volatile and dangerous fuel. Until that changes, a self destruct will be found in all large launch vehicles[1]
