Movies and TV must conform to our expectations of reality rather than to actual reality, but they also shape our expectations of reality. This feedback effect is strongest in areas where we have no direct experience to break the cycle. For instance, if most viewers have not been to Africa, their only expectations are built up by Hollywood, so they expect starvation, wild tribesmen or warlords with guns, so that's what they get shown. These expectations carry on, and it's what we expect from movies from then on. But for anyone who has been to Africa, that image doesn't match their reality, and it is irksome.
Mokalus of Borg
PS - I haven't been to Africa myself.
PPS - But I hear, from people who have been, that it's nothing like the movies.