Then why did they let the manuscript go to press without the "this study was reviewed by the University of Somewhere IRB (protocol #XXXX) and was ruled exempt"

Then why did they let the manuscript go to press without the "this study was reviewed by the University of Somewhere IRB (protocol #XXXX) and was ruled exempt" sentence? I see this enough in papers that it seems pretty standard to me, and it especially makes sense in a paper where the editors think there are potential ethical issues. If I was an author of this paper, I would have actually spent a sentence or two explaining why there was not a risk to human subjects, etc. The way they address this by basically saying it is ok because of the ToS that no one reads is the worst possible way to handle this. It seems to me more like no one thought about it at all than that the editors carefully considered it. I just don't see how you get from recognizing big ethical issues to not even addressing them in the manuscript.