Fin Fang Foom wrote:
DC has made a great effort to treat creators of older properties more or less the same as if they had signed current contracts. Granted, that doesn't always amount to big money (not every character has a clearly defined "creator," and not every character appears in media outside of comics), but DC also pays royalties on everything that's reprinted -- even when not contractually obligated. Marvel hasn't even seen fit to do that little.
I wonder how much of that has to do with Levitz and his role as publisher.  Levitz and Kahn were the ones who offered Kirby the FW royalties even though they didn't have to.  A lot of creators have spoken highly of Levitz and his dealings with fellow writers/artists.  While Johns and Lee are both creators, I can't say the same for Didio (especially given the way he's treated some pros).  Of course, now that DC's under Warner and Nelson, they may be looking at the bottom $ a lot more. 

Another possibility is that DC's original contracts weren't as all-inclusive as Marvel's.  So that when properties did branch out to new media like movies, DC had to re-negotiate new terms/royalties (like they're doing with digital).