Zombie Cliché Lookout:
Let’s say you need to search a dangerous area for some reason. Wouldn’t you start off by looking out for any potential dangers and addressing them before searching for clues/supplies/confederate gold? You wouldn’t if you were in a genre film, anyway. Whenever people are searching an area that might be infested with zombies,they just jump right in and hope the zombies have something better to do than eating your delicious flesh.
As one might imagine, the zombies invariable show up and give our protagonists trouble. Whether said protagonist survives depends entirely upon his or her importance to the plot. If they have a role to play down the road, they’re going to have a very close call, but ultimately walk away. If they’ve exhausted their potential as characters, or if their death can serve as some sort of jumping off point for the primary hero, well, it’s been good knowing you, secondary character.