Jerry Pournelle used to talk about how the old Civil Defense structures were really all about support and coordination of local groups, whereas FEMA has more of a first responder mentality.
One such commentary:
https://www.jerrypournelle.com/archives2/archives2mail/mail393.html#FEMA
True. However, if we're serious about actually making use of our citizenry, we could work that out. It would take a huge change in mentality anyway.