They are used in disaster emergency kits and deep in the remote depths of the third world since there are no batteries to go go bad. However, in a "Mad Max: Fury Road" post-apocalyptic scenario, where would any radio transmitters get their power? Or radio newscasters? As a survivor, you could have a radio that would work, but nothing to listen to. I'd think a knife or an axe or even a fish hook and some line would be more useful.
Well that's pretty obvious...wind-up transmitters.