While I agree with the fact that most captive bred animals likely come from humane conditions, or at least would hope that is true, most wild caught species will experience some sort of unethical treatment at some point or another. Whether it be in the way they are caught or shipped to not receiving the care they deserve once they arrive at the distribution center. Most of these species are not well understood or are very cheap so they be subjected to substandard conditions even once they arrive into someone's collection. I honestly think it is more likely mistreatment of animals is more common than you think.
This is very true but as hobbyist who have a deep care for these animals we must take a stand against this mistreatment. I think your stance of not buying from these sources, if done widespread through out the hobby, is a great way to accomplish this goal. Once they can no longer sell animals in substandard condition they will change their practices to match our standards, if only for the money. The way it is now if you purchase from any large online retailer of wild caught species you are more than likely supporting this terrible side of the industry.