NRS isn't used when the APS is used and vise versa - the APS is...

NRS isn't used when the APS is used and vise versa - the APS is used for those that can't communicate their pain and the NRS is for those that can. Of course there may be some people who sometimes can verbalise and sometimes cannot - the appropriate tool will be used for the state they are in. PS: you should maybe mention marketing specifically, your implication very much read as though they moved away from the APS, I am sure that wasn't your intention though......
this is also covered by the fact that APS is not used for people who can verbalise their pain. It might be time to do some proper research on how the application is being used as there are a lot of assumptions and unfortunately they are incorrect. You state there is no better standard of measuring pain than self-reporting, well the NRS is exactly that. In saying that, some people are known for twisting the truth, and when it comes to false reporting of pain, that is definitely an issue but not one I think that PCK will solve directly, however the data produced from the digital care system via PCK is highly impressive, so this would help the experts to track this and utilise their skill set to best determine how accurate the self-reported pain is.