Most of the dogs I train already have behavioral problems. In fact, a good one-third of my work involves dogs that are in some way aggressive or dominate. Head halters work best with these dogs and the results are fast without having to get violent or angry which can worsen problems. Not enough trainers know how to use them yet. Dr. Alice DeGroot had initially tried to get the word out about her K9 Kumalong in the early 80's, but people were resistant to this new approach and preferred instead to use chokes, prong collars or constant food bribery.
Dog trainers are a stubborn bunch.
We have to be to be good at what we do. It's tough to find an open minded trainer. Each believes that their way is the best way. It has worked well for them for however long they've been providing their services to dog owners. I try to remain open minded.