Unlike their microradio cousins operating on the FM dial, shortwave pirate broadcasters aren’t in the game to serve a specific community – unless you include those who’ve turned the hobby of scanning the shortwave bands into a science.
Shortwave radio broadcasting and listening is a very different sport from low power FM. Both types of broadcasters use only dozens of watts to get a signal out but FM signals are very localized. They only travel in a line-of-sight fashion, at best covering dozens of miles.
Shortwave radio, on the other hand, takes advantage of the upper levels of the atmosphere to extend their range. Using the electrically charged particles in the ionosphere, it is possible for a shortwave signal to “skip” through this layer and be heard hundreds or thousands of miles away.