First I must say that one of the things I learned from a professor at veterinary school is that no one knows their dogs like their owners and since a dog cannot talk you must learn to be open minded and listen to their owners. It has served me well many times when early in a disease process an owner was the one to tell me something's not right and by looking farther we were able to find and treat a very serious medical condition that otherwise would have ended much differently.
I respect the years of nursing care and experience you have under your belt. No one can nurse a sick puppy and save what could be a disaster like an experienced breeder.
That said we are learning things all the time about why some of the "old wives tails" worked and why they may or may not be a good idea.
People used to use used motor oil on dogs with demodex mites. The dogs that got better probably would have anyway as we know now demodex in many dogs is simply related to an immature or very stressed immune system. There were a lot of dogs that likely died from lead toxicity from that used motor oil. But those dogs weren't around to breed so less puppies with the tendency to have demodex were born. Maybe long term that was a good thing unless that pup was yours. We would have been better off and saved a lot more puppies by improving their nutrition and treating gastrointestinal parasites which weaken them further.
Breeders have used water soaked cabbage leaves or tea bags on dogs with mastitis for years and if caught early enough no antibiotics were needed. We know know that those leaves and tea bags are terrific for reducing inflammation and pain and have weak antibacterial properties.
So we must temper "knowledge" with the "do no harm" philosophy and realize just because something seems to work isn't enough evidence that they wouldn't have gotten better without the "treatment". This has happened with some of the drugs that have been introduced through the pharmaceutical companies too, not just homeopathic treatments.
Tresaderm does work, but there are mite populations that have become resistant because it wasn't used properly or people weren't willing to bathe the paws and around the ears to catch mites around the ears and on paws. The mites came back without those precautions so many people believe it no longer works, but used properly in most cases it does. Some veterinarians have given up using Tresaderm because the rate of cure is poor unless owners are willing to do the work. We know applying Revolution every 2 weeks will absolutely work with no further effort on an owner's part. Mineral oil or olive oil can "drown" the mites and may work if you have a very early infection but in most cases I don't believe it will be enough. Tea tree oil is toxic to dogs and cats, cats are more sensitive than dogs. If absorbed through the skin in significant quantities you will see drooling, vomiting and ataxia/incoordination as it affects the nervous system. Unfortunately it is all over the internet as a "safe" homeopathic treatment for all sorts of conditions. It upsets me greatly to read about it and know how many people are unknowingly poisoning their pets.
I really have to disagree with you about most veterinarians being money hungry. I'm sure there are some, as there are in all professions, but none of us went into this thinking we would be rich. We pay a huge amount of money for our education and we pay a huge amount of money for malpractice insurance. Most of us come out with a debt that takes a decade or more to pay off. And the reason that many young vets aren't willing to "work with you" is that the legal standard of care is such that should something go wrong, and you choose to sue that veterinarian, when all is said and done they would be held accountable for their treatment being "below the standard of care". They could lose their license worst case scenario or end up with a huge legal bill. In the society we are in today lawsuits are way too common so we can no longer practice as we used to, we must practice defensively. Believe me it is painful for us too to see a puppy that could be saved except that people are financially strapped. We do our best. If we have a long term relationship with a client then it makes it easier to work out some sort of care plan. If they are new to us though then we are very wary as there is no trust built up either way.
As far as using Ivomec I have to say that I simply refuse to help dose it out. We had a breeder that sent it home with all her pups. I saw the after effects of what was either a very sensitive puppy or an overdose due to misreading directions from the breeder and this poor little pup was seizuring. The family that bought the pup paid a lot for it and simply didn't have the money for us to hospitalize and treat their puppy and I couldn't guarantee that we could save this pup. It was heartbreaking for their young children to have to say goodbye to a puppy they had fallen in love with. In my mind that was a completely preventable tragedy and not worth the money saved.
Anyway now I am ranting a bit, but it is painful to be accused of being money hungry.
Best of luck with your pups.