For 75% of the typical clients you may be correct. A nice smile, a quality physique, good marketing, a pleasant personality, and some basic exercise related education can go a long way. Look at some of the people in the infomercials such as Tony Little, Kathy Smith, Suzanne Summers, etc. They make millions.
It certainly does not take a rocket scientist to teach people to improve their meal planning, weight train, train energy systems, and be encouraging.
However, a great many trainers are not sufficiently educated to work with clients who present with great complexity due to health related issues (including past/current orthopedic problems) which include most of the older population (for which the book mentioned above is written...not talking about you Q
).
Bill Hartman