It's because they appear to be the same image!
We are such amazing creations that we are wired with perceptive adaption to invert images we see from upside down to right side up like a camera lens.
By the time the image comes through your lens to the back of the eye in the retina, the image appears right side up. Your brain learns to see things right side up.
Did you know that babies see images upside down? Well, it’s true!
Over time, their brains learn how to turn the image right side up so it’s easier for them to get around.
Adult brains have the ability to flip images right side up. If you put on glasses that appear to flip the world upside down, after three days your eyes will flip the image right side up.
When you take off the glasses, the world will look like it has been turned on its head!