BraveSirRobin
Explorer
The way I choose to look at the "dead people without head wounds not being zombies" is that the infection (curse, plague, evolution?) didn't simultaneously infect every person on the planet at exactly the same moment. Thus, there was a time frame during the initial outbreak that some people became zombies, some people died prior to being infected (in cars trying to escape the reports of zombies/chaos), and some people became infected and have not yet died. As the timeline progressed, almost everyone has now become infected as the plague or whatever has had time to spread.
Just my .02 on how I rationalize the dead people in the cars and such.
This. The writer of the comic is supposedly intentionally unclear about the origins of the virus and how it really works. The point is that I don't think we should assume that it is a writer oversight. Much of it is done to create uncertainty.