Photographs are very singular and personal expressions of the world around us
They are very simple two dimensional representations of the space in front of the camera. But the experience at the time is considerably more complex.
Photographs need to capture, not just the elements in front of you, but also in some way, the feelings you had at the time. Your eyes, whilst being incredibly clever devices, are just one part of a of an amazing recording system which shapes the scene around you based on years of observation and learning.
You can see the beautiful colours in the sky whilst almost simultaneously being able to see into the shadows. Your brain ignores the background if the main subject is important to you. Colours are interpreted by knowledge. The camera can do none of these, so the photographer has to use all the tools at his disposal to produce an image that in some ways matches what he thought he saw when he was there.