That happens in the Unites States as well, especially when the professor doesn't stand to profit from book sales (and/or the author is long-dead) and the amount of reading is relatively small. I received a number of these kinds of stapled "books" over my undergraduate years. This included some from the author of one of the books in question.
I'm not sure it's fully on the up-and-up given intellectual property laws, but life is full of gray areas. At the time piracy was not the option it is today (no libgen or torrent sites, Usenet wasn't much help, and the web was sparkly-new), so those breaks were very much appreciated — especially for my classes in Attic Greek, where the relevant textbooks were now rare (though once very common) and unlikely to get much use outside of the class. We did have to buy the Loeb editions of a bunch of original texts (Greek on one side, translation on the other), but I have no issue with that, and they were readily available on the used market. I still have them.
I'm not sure it's fully on the up-and-up given intellectual property laws, but life is full of gray areas. At the time piracy was not the option it is today (no libgen or torrent sites, Usenet wasn't much help, and the web was sparkly-new), so those breaks were very much appreciated — especially for my classes in Attic Greek, where the relevant textbooks were now rare (though once very common) and unlikely to get much use outside of the class. We did have to buy the Loeb editions of a bunch of original texts (Greek on one side, translation on the other), but I have no issue with that, and they were readily available on the used market. I still have them.