Because 22 isn't a caliber military/leo uses, no one counts it as self defence, more of a trainning round. Why would there be a need for it? It's a small, cheap round, made for lots of trainning/hunting under $30 a box of 500.
SHTF vs TEOTWAWKI you ask? SHTF, just some crap on the ceiling and walls, TEOTWAWKI end of the world as we know it. Orignally made by 9mm/®™©