A) For example Germany (where I live).
B) Why do the billing practices have to be opaque? In Germany, patients often don't even see the bills. It all goes directly to the insurance company. For public insurance, that is. For private insurance, the patient pays and then asks the insurance company for their money back.
(A) which countries do you mean here? Be specific
(B) Do you think hospitals aren't trying to fleece insurers and customers all the time? e.g. with opaque billing practices?