I have heard from several people that these two games have an unfinished safari zone If this is true, what is incomplete about the safari zone?
Game Freak wanted to have a safari zone in G/S in fuschia city where it was placed in R/B/Y but late in development of the game, they decided to ditch it and leave it out. They just blocked the safari zone door; however, it is possible to get in through cheats but the only wild Pokemon you can find are from fishing in a water spot. Source: http://bulbapedia.bulbagarden.net/wiki/Beta_Safari_Zone