Topic on Talk:Command & Conquer: Generals
The availability table is meant to show where someone can get the original version of the game currently. The First Decade and The Ultimate Collection are compilation packs that happen to have the game and its expansion bundled together. Also, The Ultimate Collection bundle is currently the only digital download of the game and is currently in stores. For most people, they don't want to run around Amazon to get a copy of a game when it can be bought through a digital download service.
I wouldn't consider the games bundled in the compilation packs to be separate versions because all EA did was throw all the C&C games together on a CD and patched them all to the latest version. To be considered a separate version, it must have some fairly big changes either in-game or under the hood compared to the original retail game (see the Quake versions section for an idea).
Honestly, this is a very trivial issue.