The "Delta audit".... wasn't. The authors were not qualified as auditors by any international standard, and while interesting reading, it was not an audit comparing policy/procedures/practices against objective observations. The guys were doing the best they could do, they were also ill equipped to do a report.
......
I don't know the report, though let me 100% accept your qualification of it.
A major aspect is:
Result = (quality of the solution) * (acceptance of the solution).
I think, IF a report was written having the quality you would like to see, it would have been completely unacceptable for all involved and as such, thrown aside.
The marginal quality report they got, it got accepted internally and (as a first step) implemented. From there, the next steps would be the way to go, as has been done.
Compare that with an ISO-9000 quality system. Very nice, but the ISO-9000 doesn't have a growth path towards a higher quality level, it just "nails" the level and find out yourself, how the organization does reach the described quality level. When the step from the current situation isn't that big, it's somewhat manageable. When the current situation is pure chaos, introducing a QA system will be a nightmare and outright fail to get implemented. See my earlier writings, on how difficult it is to significantly change the culture (IE implemented QA level ....) of an organization.
Software development did go through that process, by what is called SPI (Software Process Improvement). It defines 5 levels, with each level having a lot of specific subjects to cover to improve the software development process. This stepwise refinement takes care, all the subjects get improved in a useful (and for the organization acceptable) order. The higher the level, the longer the planning horizon becomes, though. Level 1 is the current chaos, Level 2 brings you actions to describe what you have, and take care it doesn't get lost. Level 3 takes care of one start to plan for changes (and track those). Level 4 takes care of it, it's organization-wide, etc. The higher the level, the less flexible the organization becomes. Most organizations should not go beyond level 3, since it hurts flexibility too much, to be able to be competitive and react to market changes.