Comment by pwg

> Curious as to why this contract agreement needs to be secret.

Information asymmetry.

Because if Dr. X could see what Dr. Y is being reimbursed for procedure Z, and they learn that Y receives more, then in the next contract negotiation round, Dr. X will try to get more (or at least Dr. Y's amount) for procedure Z from the insurance company.

If none of the insurance counter-parties are aware of what the others are paying, they don't know if they are agreeing to less than they could have received.