Fascinating. Some of those are on my pet peeve list as well.
On the original point, I do realise that it's self-published work, but I also realise that I'm reading in Australian English while the authors are writing in American English, which is why I asked. Thanks all for the replies!
And now I have another one: what is the correct short form for "medical evacuation"? I prefer "medevac" but apparently everyone else I work with uses "medivac". At least they didn't "correct" my report. The internet suggests that both are acceptable. I'll make the argument that it should be "medevac" on the basis that it is an abbreviation of "MEDical EVACuation". What do you think? Do you think that "medevac" in either form is even acceptable written English?
The worst case of a greengrocers' apostrophe I've come across was on the entry form for a writing contest. I can't recall the full sentence, but it used "author's" where it should have used "authors". Objectively it's not the worst usage, but that it appeared on a writing contest entry form just seems so much more wrong than usual.