I’m not OP, but have worked in insurance & it’s generally not the insurance provider, but the structure of the plan. Some larger employer plans can exclude it because they are self-funded, but administered through a larger company like Cigna, for example. The employer can chose what coverage to inclide as long as they are providing the minimum coverage mandated by state and federal laws. This is how some companies can also deny coverage for birth control and other things that would logically seem medically necessary. I had this kind of employer-based plan that was administered by BCBS & excluded all breast surgeries except as directly related to breast cancer treatment