Because the whole shot was recomposited. The starfield, the planets, and the ships are all separate elements. Whoever recomposited the shot left the matte lines the same as the LD release, didn't overdo the blue flare like the 2004 DVDs, and used the same starfield as the 2004 DVDs - which we now know is the original starfield from '77. Seeing as they either digitally created the opening crawl or used the same one as the Empire of Dreams documentary, the starfield used on the crawl/pan down/opening shot is the original and not the one from the pre-SE home video releases.