Why do trainers not compare philosophies when they seek certification(s)?

They probably don't know what to look for! When I started as a fitness professional in 1995, few certifying agencies existed. I was certified during NASM's early days, giving me a science-based foundation in biomechanics, physiology, anatomy, nutrition - even physics as related to weight training. It was excellent foundational coursework given by experienced and passionate professionals. Since it was begun by a physical therapist, healthy and safe movement patterns were emphasized. (Incidentally, Tom Purvis was involved then - awesome!) When NASM moved toward "functional" training, it gave me a new understanding of physical conditioning of the body as a whole, rather than the parts. However, I found neither phiolosphy satisfied all of the needs of my clients. I then began studying various movement modalites such as Feldenkrais, yoga,Qigong, & especially Pilates and further needs were met with different styles of flexibility, stretching and assessment techniques. But there are varying philosophies amongst each of these! I also sampled many training concepts at IDEA and other industry events and learned something from each. EVERY modality has it's pluses and minuses. I even added TRX and Power Plate certs to the mix because each makes its own unique contribution to my clients' wellbeing. Nearly every modality is valid and has an important contribution to make to human movement. As a 2011 Gray Institute GIFT fellow, I am finally tieing all the pieces of the puzzle together! Movement science, as understood by Gary Gray, makes the connection clear between ALL certifications because it IS the foundation for all human function. The only truely BAD certifications are those that A) teach you dangerous techniques, B) make you think their system has the only answers (it's not true) C) Is interested in profit over producing quality trainers. Unfortunatly, you don't always see this until after the fact.