I once had my life insurance refused because I casually mentioned to my family doctor that I tend to remove my mask during the night, so I don't use the CPAP regularly. The life insurance company called my doctor and use that information against me. Image how much worse this can be if the doctor has compliance information all the time without asking for your permission.
Also, in some countries certain professions require compliant use of a CPAP if one is diagnosed with apnea (such as professional drivers). If compliance information is sent to the doctor automatically, and you are a professional driver involved in an accident, the government could subpoena ResMed to get your compliance information, and use that against you.
So why go through such legal and insurance risk when the doctor can so easily get your information with your permission via an SD Card? It blows my mind!