Foundation Repair Salesman: Licensed to Kill

I would like to know who established the fact or policy that a Foundation Repair Contractor is an authoritative figure able to pass judgment on the condition of a home, such that a buyer can take the contractor's evaluation/judgment and retract his offer, demand that the seller either make the repairs the contractor is proposing, or demand his earnest money back and walk away from the deal/contract. Who did this? Who established this policy? 

I have spent the last five years looking at hundreds and hundreds of houses that were claimed to have major structural damage or foundation instability or were "literally sinking into the ground" by an assortment of foundation repair contractors in and around Huntsville-metro.  I cannot think of five that had any such problem!

The claims were completely fallacious, unfounded and "biased!"

What do I mean by biased? Unethical, mainly! Because there was no merit or technical basis for their claims. I've been told that foundation repair contractor salesmen, that visit homes to "evaluate their condition" are paid strictly commission, such that if they don't sell, they don't eat, don't pay their mortgage or save for their kid's education! So, you tell me, does this work arrangement entice the salesman to sell? You bet it does!

Who is this salesman? What are his qualifications for assessing foundation damage?  What would you "expect" to be his/her qualifications?

I contend that no one other than a licensed professional structural/civil engineer should be able to articulate why a home has a foundation problem and why it needs to be repaired, or more commonly, why it doesn't!