Right you are. Non-professionals are not coming out of the seminar ready to hang up a shingle. People with various backgrounds take the seminar. Most are eventers who want to learn a few moves to work on their own horses. Others are human chiropractors and vets who want to add these techniques to their practice. What you said about your chiropractor is true--they go through a long program that takes months. What is also true is the vast majority of trained animal chiropractors, who are first licensed human chiropractors, cannot legally practice what they learned due to state law restrictions on adjusting animals other than their own. The result is bunch of qualified chiropractors all dressed up but no where to go. Thus, horse owners cannot find a qualified horse chiropractor willing to risk their license to come out and work on their horse--so they want to learn a few moves they can do themselves. Or at least recognize when their horse needs chiropractic care. While we're at it, I don't know any horse owner who doesn't know at least a dozen medical procedures they do themselves--such as suturing, debriding, injecting, and so on. They had to learn that someplace--but you don't see them hanging out their vet shingle. They learned those procedures out of necessity or due to the cost or paucity of vets in rural areas. | 
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