Sandy,
You seem to be thinking that the comment "USPAP is promulgated for appraisers and users of appraisal services" to mean that the ASB can enact standards for the conduct of the users of appraisals.
If so, the ASB would have to have the authority to compel users to comply with our standards. However, one look at structure of The Appraisal Foundation should put that notion to rest. TAF is not a governmental entity. It doesn't have the right or the ability to make, judge or enforce law or public policy. The only way USPAP becomes an enforceable standard is when a governmental agency or jurisdiction accepts or adopts it, when it's required by contractual agreement, or when the individuals decide to abide by it.
In short, the ASB doesn't force anyone to do anything. The state appraisal boards and the federal government do that via licensing requirements. The ASB just establishes appraisal standards that are used by other people, much the same way the Financial Accounting Standards Board establishes professional standards for the accounting profession. There literally is no USPAP police.
Instead, the term "for appraisers and users of appraisal services" means exactly what it says. USPAP is intended to delineate appraisal standards - how to conduct oneself while performing and communicating various appraisal services - for the benefit of appraisers and users of appraisal services.
It is obvious that the users of appraisals don't perform appraisal services, which is why USPAP does not apply to their conduct. The way that users benefit from USPAP is that it provides a set of standards they can use to see if the appraisal services they are getting conform to our minimum requirements and are thus suitable for their usage.
One example of how a user of appraisal services can benefit from looking at USPAP happens when they suspect an appraiser is pulling their chain about what they can and can't do. For instance, when an appraiser declines to accept an assignment with a contingent value requirement and cites the Management section of the Ethics Rule as their reason for not cooperating, that client can go to that section and read it for themself. In that way, they can determine that the appraiser is not just being stubborn or antisocial but does in fact have a legitimate reason for why they cannot do as the client originally requested.
The same can be said for any set of professional standards. When I go to get a haircut from a licensed barber who is abiding by their professional standards, I as a consumer am not subject to those standards, but I do benefit from them to the extent that I can demand that barber act in conformity with them.
Get it?