No, that is not the case with IATA's RPs. Not every airline follow IATA RPs on every point. It is not a requirement of being a IATA airline that you follow all RPs.
As far as I can judge, what you have reprinted are BA's instructions to airport agents in NA. They do not form part of the contract. There is a difference between what an airline will do as a matter of operational practice, (which may be, and usually is, more than what the contract provides) and what your contractual entitlements are.