The point is rather if you’re operating an FM transmitter, you not only have the money for a satellite dish and DVB-S decoder you already have one, and FM radios are dirt cheap. The electronics for short wave certainly aren’t more expensive but you’ll need a proper antenna. Meanwhile, much of Africa actually has quite decent mobile phone coverage, there’s some piss-poor countries and large areas of nothing, generally desert, but overall, if there’s people, there’s probably reception. Their whole banking system works via mobile phone.