Astute observation! There is more to herd dynamics than just dominance and subordinance. There are often peer to peer relations with horses. Or horses that do have dominance over the others , and you will see them occasionally assert it, but for the most part they do not . They may allow the ohter to eat or drink right next to them. They often have several attendant that follow them happily.
I do not think a person has to look at ever movement or touch a horse makes on a person as him trying to assert dominance or testing.
The thing that cannot be allowed to go uncorrected is when you ask the horse to move his head or shoulder and he DOESNT! Or he pushes back. Then you must firmly reset his understanding of where he resides with respect to you on that ladder.