Why do we need qualitative assurance?

The following is an opinion-piece I wrote on prizmablog, in response to a post in which the author identified the lack of qualitative assurance for GRI-style sustainability reports. I've tweaked my comments for clarity.

It's high time for a North American group to develop a recognized qualitative assurance program to address the tick-boxing syndrome caused by the most common sustainability reporting assurance programs. Companies can currently have their reports checked by the big four auditing firms, third-party consultants or the GRI itself, but none of these services are "designed to provide any verification or assurance of content or quality of processes applied" (Nazari).

This, in my view, reduces the effectiveness of GRI and sustainability reporting in general. It also represents value lost for reporting companies.