Why do people think Africa is a country?

Not entirely true. There is a country called Central African Republic and Nothern Africa, and the entire continent of Africa for that matter, was never one country it was a provincial region. There was a Roman province of Africa but I doubt that people are referring to that when they mistake Africa to be a country. I'd say it was ignorance.

You misunderstood. I was simply saying that it's not so much that people think Africa's a country, but they just call Northern Africa, Africa, out of laziness.