The reason why it is hard to make a map of the world is because it is hard to make a round shape perfectly flat. Just think of it this way: When you draw a map of North America, you do it in a flat sheet of paper. Although you try to make the area bigger, it is still considered as small as opposed to the actual size of North America.
Also, since Earth is a sphere, when you draw a map on a sheet of paper you tend make the area distorted or stretched. Hence, you won’t be able to make an accurate drawing of a map. Take note of this: Greenland is made to appear as the same size as Africa, but in reality Africa is way larger than Greenland.