I agree, Martin.
All work is a process, and all processes have variation. Inspection is a process, and it has variation. If our variable production process is making the occasional bad product, we depend on inspection to find it. But, our inspection varies, too, so some bad product may get through to our customers.
The inspection, then, would not be value added, unless the customer was willing to pay extra for it.
However, if the prevention part of the equation reduces inspection and/or improves outgoing quality, then IMO it would be a value-added addition.
Craig