Warning, there are a lot more zombies in the game than the show (still not like an insane number, just more). It's different in a way really. The stakes in the game are lower, you can heal yourself and all that, so having a bunch of zombies isn't really death. You can also start at a checkpoint if you die. But in the show the characters can't just heal, and the stakes are low if they can just fight them off easily and or evade them. So by making the zombies scarcer in some ways in the show, but they make those encounters extremely deadly in the show to advance the story. They play a role to telling the story, but are not the point of the story.

Also, the game is an action game, so, naturally, zombies are more plentiful or it wouldn't really be an action game so much.