CPAP is in the category Durable Medical Equipment. That aspect of Medicare coverage has been subject to horrendous levels of fraud. To try to counteract that Medicare requires physicians to physically interact with the patient. One set of rules for all DME coverage. To slice out exceptions and variations would lead to a mess. Medicare is constantly trying to balance efficiency and fraud prevention. Patients like us get caught in the middle.
Also, to my knowledge FDA rules prohibit ANY prescription being issued without a direct contact between patient and doctor.
One of the major issues CPAP users complain about, as posted on cpaptalk.com, is the fact that doctors provide very little direct support for CPAP patients. Many make adjustments in the CPAP settings for themselves based on what they see in the data from their machine.