From the inside front cover of my ANSI A119.2/NFPA 1192 Standard on Recreational Vehicles 1999 Edition.
"IMPORTANT NOTICE ABOUT THIS DOCUMENT"
The RVIA and the NFPA codes, standards, recommended practices, and guides, of which this document contained herein is one, are developed through a consensus standards development process approved by the American National Standards Institute. This process brings together volunteers representing varied viewpoints and interests to achieve consensus on fire and other safety issues. While the RVIA and the NFPA administer the process and establish rules to promote fairness in the development of consensus, they do not independently test, evaluate, or verify the accuracy of any information or the soundness of any judgments contained in their codes and standards.
The RVIA and the NFPA disclaim liability for any personal injury, property or other damages of any nature whatsoever, whether special, indirect, consequential or compensatory, directly or indirectly resulting from the publication, use of, or reliance on this document. The RVIA and the NFPA also make no guaranty or warranty as to the accuracy or completeness of any information published herein.
In issuing and making this document available, the RVIA and the NFPA are not undertaking to render professional or other services for or on behalf of any person or entity. Nor are the RVIA and the NFPA undertaking to perform any duty owed by any person or entity to someone else. anyone using this document should rely on his or her own independent judgment or, as appropriate, seek advice of a competent professional in determining the exercise of reasonable care in any given circumstances.
The RVIA and the NFPA have no power, nor do they undertake, to police or enforce compliance with the contents of this document. Nor do the RVIA and the NFPA list, certify, test or inspect products, designs, or installations for compliance with this document. Any certification or other statement of compliance with the requirements of this document shall not be attributable to the RVIA and the NFPA and is solely the responsibility of the certifier or maker of the statement.
NFPA is the National Fire Protection Association
RVIA is the Recreation Vehicle Industry Association
So based on the disclaimer... the RV manufacturers come up with the rules. They don't make sure the rules actually work. They aren't held accountable for the rules they come up with. And they don't have to follow the rules.
Btw, elsewhere in the book (the front page under "Notice") it says "The ANSI A119 Accredited Standards Committee was created to establish minimum requirements for the installation of plumbing, fuel burning, electrical, and other safety related systems in recreational vehicles." So remember... these are the bare minimums.