In "The Democratic Forest," William Eggleston wrote:
I am afraid that there are more people than I can imagine who can go no further than appreciating a picture that is a rectangle with an object in the middle of it, which they can identify.
Consider a photo your parents treasured: you, on a department store Santa's knee. If you were properly exposed and in focus, your parents liked it; bonus if you had a cute expression.
We call this kind of picture "hierarchical" because some parts of it matter more than others
You come first. Then comes Santa, a distant second. The background - Santa's chair, the wall behind him, etc - barely count at all.
Eggleston uses the word "democratic" in two different ways. Most obviously, his work is "democratic" with regards to subject matter. ANYTHING was worthy of being photographed: shoes under a bed, the contents of an ice box, discarded milk jugs in an alley.
The other meaning of "democratic" applies to the picture space itself. In an Eggleston picture there is no subject and no background; everything is equally important. I once watched Mr E go through a dozen envelopes of drug store prints; in addition to looking at them right side up, he also flipped them, the better to study the pictorial content, divorced from it's IRL "meaning."
In the header picture, it's (hopefully) impossible to identify "subject" and "background" - you can't change one piece without changing the whole.
When I posted it on Flickr, it got quite a few "likes." That's not because the Flickr community is filled with high modernists applying rigorous formalism - people liked the 60s furniture and colors scheme. A few times I've tried posting shots composed "democratically," but without interesting subject matter; they where staggeringly non-popular.
The Great Man himself is not above concerning himself with subject matter: you wouldn't print a portfolio called "Troubled Waters" featuring a neon confederate flag if you weren't. That said, the photos in "The Guide" seem deliberately chosen to be, paraphrasing Seinfeld, "pictures of nothing."
The ideal "art" photograph provides more than instant gratification; it rewards multiple viewings. When color photos are composed hierarchically, they tend to look like postcards or advertising photos.