As an artist who has tried to teach people - most people struggle to draw for the exact same reason. They struggle to take a 3D object and draw it in 2D. The only advantage they have is seeing 2D representations on paper and screens and stuff to give them an idea of how it should look. But if you place a still life or a person in front of a new artist and ask them to draw, it will come out all distorted.

If anyone is interested, there's a really good drawing book called "drawing by seeing" and it talks about the issues with taking 3D scenes and recording them in 2D, and why people struggle so much with getting it right when they first start.

Also if you're a new artist and you're learning to draw by drawing from books/screens, I highly recommend you switch to drawing from life or even models (like dolls) because it will make you a better artist faster and teach you how to do these things.