They also could have pressed a ton of discs to the point it exceeded the initial demand. Fox apparently gave a lot of unsold full screen stock away to charity. These discs have the UPC slashed and a sticker pasted over it:
http://www.ebay.com/itm/Star-Wars-A-New-Hope-2006-Limited-Edition-Full-Screen-2-Disc-DVD-Sealed-/282447595167
http://www.ebay.com/itm/Star-Wars-The-Empire-Strikes-Back-2006-Limited-Ed-Full-Screen-2-Disc-DVD-Sealed-/272645545378
http://www.ebay.com/itm/Brand-New-Star-Wars-VI-Return-of-the-Jedi-DVD-Full-Screen-LIMITED-EDITION-/262833889091
You can still find a lot of early DVD titles in bargain bins these days. I doubt Warners is still pressing flipper discs of the Batman movies for example.