In the end photography is about capturing light. Some would argue that the lighting is in fact more important than the subject.
Personally I differ, I think that it depends on several factors. Some genres of photography are subject centered, for instance, with any sort of documentary photography capturing the subject is the primary goal, if the lighting happens to be perfect that’s just a bonus.
On the other hand, a photo like this is all about light. Without the evening sun filtering in from behind, this photo would be worthless.