Well if you believe in conspiracy theories, Netflix subtly alters the film so that if it shows up on Bittorrent they know where it came from :-)

But I suspect that Netflix isn't doing the altering, rather their source material comes that way. Either because the distribution channel gets it that way or because the content providers want it that way. Like the author I suspect that if it wasn't being done by the media companies there would be a big stink about it.