George Romero’s “Night of the Living Dead” is a perfect example of what happens if ideas are not owned. First, as was the case with “It’s a Wonderful Life”, the film became popular because all theaters could show it – it had no copyright.
Second, unlike the classic “Frankenstein”, everyone can use the likeliness of zombies to create their own remixes and versions, which spawned and will spawn great works like “The Walking Dead” or “Shaun of the Dead”.
Am maybe most importantly, the lack of copyright didn’t outshine George Romero’s work. He went on to make money, movies and became world famous.