That idea would never fly in the United States and it's better that way.
Farrier's quit on horse owners for a variety of reasons.
1. Mine left after 4-1/2 years because they got P.O.'d when the vet ordered my foundered horse to his clinic every five weeks for shoeing by his farrier. They (brothers who work together) could have still done my other horse. I am not out of their way, but they chose to get all up on themselves and quit without notice.
Under your suggested method they could have been forced to come back. In times past, I have experienced first hand what a "vengeance trim" can do.
I would put my foot down to your proposed method and lobby against it, if it came to that.
2. There are many owners who refuse to work with their horses to keep them mannerly for the professions whose service they pay for.
I have yet to talk to an established farrier with an above average rating, who gets excited about trimming an unruly horse that likely will try to kick them. Good farrier's don't have to come back and put up with a horse like that, and they shouldn't have to.
If the horse is difficult about picking up any one or all of its hooves, it is the owners responsibility to fix that problem.
Sometimes it is a pain issue. Sometimes it is a behavior issue.
Regardless. The owner needs to get some dirt under their fingernails and fix the horse for the farrier.
3. You are essentially wanting to form a union for farrier's by insisting that everyone carrying a set of kippers and a rasp must join. It is good for farrier's to go to school and become certified but forcing them into a "pool" is just wrong on so many levels.
3.1. As an aside, one of the advantages I have, is that I have trimmed my own horses off/on for a lifetime and can always keep them tidied up in an emergency. Horse owners that are physically capable should learn to do a little trimming, and how to pull shoes in an emergency.
4. Farrier's might also quit because the owner isn't doing their part to maintain the hooves between farrier visits. Such as pick the hooves or watch for and treat thrush if it develops.