Australia, New Zealand, and UK Air Forces' rank names are unique too, unlike North America's. So I focus here on the Canadian and US Army, Air Force, and Marines ranks that are the same. Why haven't the Canadian and US Navies standardized or equalized their ranks with their other branches?
Outwith onomatopoedia and sound symbolism, "most words are arbitrary with regards to their meaning". So I don't understand why the Navy requires its singular rank names. Or is this all merely an affair of tradition?