The doctor has already managed to find time for the service - she’s seen you. Potentially even done the procedure. The hospital has made room for you. The resource is already consumed by you, like a restaurant meal. The question is who is picking up the check, when you already have a subscription service paid for.

The service is not “free healthcare for any procedure ordered by a doctor all the time without limits”, they have the right to refuse something they feel is unnecessary

And the doc is also spending a shocking amount of their time on the phone yelling at the insurance company flacks, as a bonus.