Quite often actually. I work in pharmacy and often for drugs like Ondansetron (a nausea drug) which is covered under part D and part B they will automatically reject the claim unless you can prove its not being billed for a part B purpose. However if you need it for a part D purpose you can’t wait the couple of days for the doctor to get it approved by the insurance so these patients end up paying out of pocket and never being reimbursed, which is exactly what they want.