I had to laugh. As a US government report, the Mueller Report is public domain in the US. KDP has strict rules on having only one public domain edition available for sale unless there is unique content (translation, annotation, or illustration) which must be identified in the title metadata.
https://kdp.amazon.com/en_US/help/topic/G200743940. Having something like an introduction explicitly doesn't qualify.
Imagine my surprise to find several different editions of the Mueller report available for sale. Here are a few of them:
Three at $0.99. One has two forewords, one by a Republican and one by a Democrat. Off-hand, it doesn't seem to qualify, but it has a bestseller banner. The second shows the length of the redactions. KDP rules explicitly deny that formatting differences make a work unique, so this one is dubious. The third one has a foreword. Again, it doesn't seem to qualify.
One at $1.99 from Penguin-Random House. It doesn't identify any unique content (in fact, it seems to disclaim having any) and has a publication date later than the three listed above, but I guess its OK because...Big Five.
One at $2.99. It's a print replica that explicitly says it has no other content. I assume someone just took the DOJ-released PDF and made it into a Kindle book. How could that qualify?
Another at $2.99 that appears to be a print replica or close. The TOS identifies no unique content.
Oh, yet another at $2.99, another bestseller that, like some of the others listed above, makes a virtue of having no unique content. The pitch is basically that commentary could bias potential readers. It could--but we only need one edition without commentary, not however many we have.
One at $7.99 from Simon and Schuster. It has not only an introduction by Alan Dershowitz but also "The relevant portions of Title 28 of the Code of Federal Regulations, the 1999 provisions written by former acting Solicitor General Neal Katyal, which establish and regulate the powers of the special counsel; Rod Rosenstein’s 2016 order appointing Robert Mueller III as special counsel and outlining the scope of his investigation; Attorney General William Barr’s four-page summary of the report, as sent to Congress; Barr's explanation of the four reasons for redacting the report, and a key for identifying them in the color-coded report." OMG (as my students used to say), here's an edition that actually qualifies as having unique content under the KDP rules.
On at $7.99 from the Washington Post. "The only book with exclusive analysis by the Pulitzer Prize–winning staff of The Washington Post, and the most complete and authoritative available." (At least Bezos follows his own rules.)
How many editions are there? I stopped counting at fifty. Some of them are so obviously just the PDF converted to Mobi that the cover is the title page of the report. A few of them offer what might be unique content under the rules, but most don't seem to. Prices range from $0.99 to $14.95. I counted I think five bestseller banners (in different categories, which seemed relevant but were a little "creative") I also notice one on Amazon most read chart and two on the most sold chart--but at least those three are all within the rules.
What's in the first line of sponsored product ads on some of the product pages? Several more editions of the Mueller report, some with newly released labels on them. So not only is Amazon allowing multiple editions without unique content, but at least some of them got approved for AMS ads.
To be fair, it looks as if Amazon got hit with a tidal wave (or is it title wave?) of several of these a day. However, it's clear that there is no effective automated system that checks the submissions to see if they are repetitive public domain works.
Most of the repetitive titles are indie or small press, aside from the Penguin-Random House anomaly. Of course, it's possible many of them didn't look to see if other copies were available before clicking publish, and one of them (whoever was first) would have been entitled to publish anyway. Since several a day were being published, an early submitter might not have seen the several others submitted on the same day. Still, the later ones should have checked.
So yes, some of the folks with editions up needed to do their due diligence. But Amazon should include a check for the same title on public domain submissions and then kick any potential conflicts to manual review.