I'm sorry, David. I was too abrupt and baseless in my answer. My usual explanation for my students when I don't have an answer is to say that the language is alive...it is evolving. Part of the problem is that the rules are different in different parts of the world and in different eras. I really don't want to research this one for you, but the reasons often have to do with ease of speech. We get used to saying something one way and it becomes something of a collocation.