> Unlike patents, it’s very possible for two independent people to come up with the exact same sentence and those people to independently own copyrights to the exact same words. Proving independent creation may be difficult, but it’s still possible.

In cases where this is possible, it's often not possible to hold a copyright over the phrase for reasons of lack of creativity. The main difficulty isn't proving independent creation, it's proving that a third party didn't also come up with the phrase independently.