I am running a custom campaign in this game (not one of the ones in the book) and I have been using the zombie stats for the "zombie" from the No Room in Hell scenario. they have a DEX of 1 and as such, barely ever hit and when they do they only do 99% of the time 1-2 stress, which is usually quickly absorbed by the PC's since they often have 1 or 2 resistance vs. physical stress depending on how stressed they are on that track at the time. This is even the case when using large hordes of zombies against the PC's. This means these zombies will never push a PC to have to convert physical stress into trauma and thus possibly suffer the special effects of a zombie bite.
Are you all experiencing the same issue and if so, how are you dealing with it? I'm considering mixing in some of the ghouls as found in the Night of the Meteor scenario. They have a DEX of 3, making them much more deadly than the previously mentioned zombies.