I just read a new book by John Powell, a physicist and musicologist from England. It was called "Why you like music", or similar.

He said that a person can only copyright the melody of a piece of music. (Ergo, we cannot copyright an arrangement.) It makes sense. He showed the math of four flutes playing harmonious notes on this simple phrase:

ba ba black sheep have you any wool?

There are over 250,000 possibilities.

That makes it clear why governments do not commit themselves to keeping track of arrangements, but why don't they come out and say so?