Well, that's interestings... Lets see, 'Return of the Living Dead' comes to mind...
night of the living dead....dawn of the dead(orig)....day of the dead
I think this is all just part of the movie reality they try to create. If a real outbreak happened most people know what zombies are. Even your average valley girl would know getting bit is bad. In the movies zombies were never created in the fiction world so no one knows what they are. I can't think of many movies that break this trend.
Zombie Girls, they may be dead but you'll feel alive.