How much of that is due to the map projection? And how of that is due to the fact that most Americans are very poorly educated about Africa; and we tend to compress things with which we're not familiar in our minds. Even I'm guilty of it. Just this year I re-discovered the fact that not every country of okay with endless suburban sprawl. So they build their cities BIG; such the population of San Francisco, which is "the" city to me, could be a mere neighborhood. And no amount of studying the map and photos so I'll know where stuff is prevents me from being startled at the actual scale when I get to what the rest of the world calls a city.
And let's be real. There are more than a few Americans whose entire concept of Africa is: ancient Egypt, The Lion King, Sally Struthers, the Sarah desert, Busch Gardens, if they're a particular chest-thumping sort they'll know about the "great white exlorer/hunter" era and Patton's North Africa campaigns, and terrorists.
Until you've actually been to a place, that place compress in the head very easily even if you know better and try to fight the tendency. A lot of people neither know or try. To them, the whole continent probably fits on a largish GTA map.
But still... inflated poles notwithstanding, it is clear that Africa spans something like 70 degrees of latitude. That's frikkin huge, and quite obviously so.