Why would anyone adopt this system, even as a backup, when the postal system already serves as a backup communications network? And has already proven its perfo

Why would anyone adopt this system, even as a backup, when the postal system already serves as a backup communications network? And has already proven its performance? And in such an extreme scenario I imagine roughly no adults will care about any ‘content’ at all, food, water, and shelter would overwhelm all other nice to haves.