I will respectfully disagree. There are those out there who "dig deeper" so to speak into the origins of certain skills. Many of these can be found in the
Bulletin of Primitive Technology of which many of the articles are compiled in the books
Primitive Technology and
Primitive Technology II by David Westcott.
I give a lot of kudos to Cody Lundin as the approach of both of his books take it to a different level in that they are both technical and philosophical in that you are learning how to learn. This is especially true in his second book. The McPhersons and Mors' books are heavily based on practical knowledge and obviously Larry Dean Olsen's book is an original. These are a few examples.
The books out there where the info is rehashed are more or less technical manuals. If this, do that... very military in its approach. I mean no disrespect in that statement, but you can see it the military training (technical) manuals being transposed into many books. Unfortunately for the military when it relates to survival, they get little survival training as they are learning/responsible for so many other important skills, thus they have to be very practical (technical) in the approach.
Going off on a tangent here... this makes me (anyway) lend more creditibility to those who have and continue to make a living in teaching survival/primitive skills (including military survival instructors) than those who are just military trained. Sounds like a good premise for a TV show... wait... there already is one.