I couldn't justify making it more complex than it is, based on one aspect - that of internal auditor training - which has apparently failed. For the vast majority of businesses, all over the world, someone can define competencies for those who do work affecting product/service quality. In which case it is just as simple and I laid out.
In the case of internal audits, which aren't institutional to the vast majority of businesses, there are few providers who know what internal auditor training should be. A significant proportion of training is nothing more than external auditor type training. Often, the training is delivered and modelled on what the trainer sees CB auditors doing. Even the accreditors of such training don't fully understand the difference (or if they do, it's not apparent in their approval of the materials). And, of course, many, many CB auditors don't see anything wrong when they got the same type of training... This is a far more complex situation than determining competency for a shop floor operator, in manufacturing, for example...
In the case of internal audits, which aren't institutional to the vast majority of businesses, there are few providers who know what internal auditor training should be. A significant proportion of training is nothing more than external auditor type training. Often, the training is delivered and modelled on what the trainer sees CB auditors doing. Even the accreditors of such training don't fully understand the difference (or if they do, it's not apparent in their approval of the materials). And, of course, many, many CB auditors don't see anything wrong when they got the same type of training... This is a far more complex situation than determining competency for a shop floor operator, in manufacturing, for example...