Because using Casino Royale there are too many ifs between the screen and the test pattern source. For example what is your source, what firmware are you running on it, does it have any know display bugs, is it set to over scan, is it sending the signal over analog or digital, was the disk encoded correctly... All this may or may not matter you're just left with a lot of speculation. There are fewer things that can go wrong with an internally generated pattern or one generated by say an Accupel signal generator.
Human perception is not a direct consequence of reality, but rather an act of imagination. - Michael Faraday