Yea Im not a big fan of the zombie survival guide...infact I pretty much think Brookes is a hack. I mean he does have some good ideas in the book, but I think those are mostly educated guess' on his part. Im not going to get into all the reasons I think Brooke's book is horrible, cause that tends to start arguments on here. I will however give my argument for the wilderness argument.
The very first thing to learn is that how a pandemic spreads. If zombies are what we all have come to know, and fascinated with the virus that infects them will spread fast. Do you remember swine flu acouple of years ago? I had just started working as a paramedic at the time, and I watched the medical community struggle to keep up with hysterical panic that at the time wasn't needed. I know though, that swine flu started showing its face in Mexico and very quickly (24 hours) had turned up in areas like Chicago, New York, Orlando, LA, and large cities. It quickly moved into smaller towns from there. With the global society we have today, the spread of disease can not be contained. With a rapid spreading disease the vast majority of our population would be infected with in weeks. Survivors would be very few and far between.
Something else to take into consideration is the fact that eventhough the world is populated, and built up we still have less that 25% off the world cultivated into anything. There are hundreds of thousands of miles in this country alone that have not be accurately mapped.
Third....a lot of people have no idea how to survive out on their own in the land. So many people won't stray far from civilization. I recommend to anyone to learn how to self sustain. I learned from my dad and grandpa, and the united states army. One of the first things taught in evasion and survival school was getting out into the country side. Less hostiles, and more resources to eat, and survive.