Goodreads Librarians Group discussion

I have a question about the books sold as sets with ISBNs. When they come with a case and are truly a set it makes sense. However, there are several "sets" where they have taken whatever books and are selling them as a "set". They are quite obviously from different publishers. I can guarantee the author is not making a profit on these. It just seems really skeevy.
ISBNs aren't that expensive for someone looking to scam people. Has this ever come up before where the books were never lumped together, but a seller went and paid the $125 fee? With how little oversight there is at certain retailers I imagine people are making quite a tidy profit.
I feel like if the covers in no way match and the books are obviously different sizes how is that a "set"?

I would be interested to know what your source is. If it is unauthorised reselling then it would be an issue indeed. But I haven't seen any publisher or authors I follow on social media warning about their books are sold in these sets.
Also, unless they are selling actually pirated copies or such they must obtain their books like any other bookseller, how would it harm the author if a bookseller buys books to sell them only in sets?

If there are actual legal issues with these books, legal issues are handled by the staff.