There's a big turnover in editors, just like there is a big turnover in mystery shoppers. Some do it for years but others drop it after a few weeks or months. I bet the more experienced editors are most likely to include the phrase. Having mystery shopped myself, all the reports I have done that were accepted by the MSCs were also accepted by the client. When I briefly edited, I was appalled to see the times I accepted a report because it appeared to have been done according to the guidelines. The first time I accepted a report that a client declined, the client provided us the video and it was clear that the mystery shopper lied massively on the report. There were other instances where I accepted a report that looked great but it turned out the report did not reflect the whole visit and it was not accepted. So, realize that the editor sees only what a mystery shopper submits. They correct grammar and spelling and look to see if your report appears to have followed the guidelines. The client has video and can track a transaction through receipts, etc., and the client can identify issues the editor can't see.
When I got to be a more experienced editor, I started to add that phrase. Sometimes things happen in a shop that the editor doesn't see and the mystery shopper doesn't realize is wrong, or the mystery shopper thinks it's a little mistake and doesn't bother to disclose it in the report. Then there are the unethical, deliberately dishonest shoppers who figure if they write a good report and get it past an editor, they have it made and won't get caught.
One woman did not perform the shops, she just walked around collecting names and wrote a fake report. Watching her video was horrifying. Another took 2 people with her, although she was supposed to shop alone and it was like a social event rather than a shop. Another took a toddler with her when children were not permitted and she spent a lot of the shop time fussing with the toddler. When she was told that the client's video showed she had a child with her, she initially denied it, then said it "wasn't important, because I did the shop, did a good job, just look at my grade from the company, and having her with me didn't impact the shop." I saw the video, guys, it impacted the shop.
Almost all mystery shoppers are honest and want to do a good job, and hearing about dishonest mystery shoppers is probably a shock to most of you who are reading this. I know it was a big shock to me.