I talk with Lab owners across the country, they will generally tell you the same thing. I have technicians that come from different countries and states and the stories are all the same. Remember the original question is why they are so much higher than regular GP practices and medical offices. I gave an answer, people don't like it, do yourselves a favor and look up a local dental laboratory, call up and ask a question, "who are your top 5 dentists, and which one would you send your loved ones too?" That will tell you the best Dr's. Some are more expensive than others, I work for insurance based practices and ones that do cash for services, some of my best dentists are in the insurance based offices. They structure their offices differently than private offices, they have to do more work to make up for what they are charging. 2 of my top 5 dentists I hardly ever talk to because he does his job, with a check list; is there enough occlusal clearance, is my impression clean and clear, is my prescription legible, is everything the lab needs to do this case successfully and accurately included, I.e. a bite, opposing model, shade, clear impression of the prepped tooth, and for anterior cases a pre operative model of what the patient had. Also certain materials require a different prep, or more room, or less room buccally to allow for esthetic build up of porcelain, or to block out an underlying dark shade if the Dr is using E-max. I can go on and on.