I think that you are a member of a very large club!I, of course, don't know.
Yep, perhaps one or more of those (and there are probably many other possibilities, too).Perhaps they have not encountered cut-out fires (to little room and oxygen?) so they did not bother.
Perhaps they suggested it to the regulation body but they said "Oh we'll just go with metal ones".
Perhaps they are in a fierce battle with the DNOs who flatly refuse to have metal cut-outs.
Kind Regards, John