The point is, ink extortion seems to thrive on pricing tiers for different markets, just like content extortion does.
https://www.scotusblog.com/case-files/cases/kirtsaeng-v-john...
Could this format be designed to satisfy some local expectations as to the look and feel of a "quality" book?
It’s not "some" books get one and others get the other. All books get out in a first format decided by the publisher. There’s no "default" format; it can be big or small depending on the author/publisher’s choice. Then, later, you have reprints, which are often (but not always) in a cheaper format, the one we call "livre de poche" and which sells for less money. But this reduced price has little to do with the format; paper doesn’t account much in what you pay for a book. When you do reprints you have reduced costs everywhere because the text is already there: no need for a translator, reviewers, etc; also, there’s no marketing and the author’s fees are usually lower. In fact, in Italy, reprints are cheaper even if they are usually printed in the same format as the first edition.
A lot of the keys sold on various sites come from those regions, some companies iirc Ubisoft started implementing region locks.
Region locks on DVDs other than due to issues of distribution rights especially for dubbing and subtitles followed the same logic especially in Russia where region locked DVDs were released much earlier and for much cheaper as piracy was far more common there than in the west.
And a dire warning about where the book may be sold.