Suppose I check an e-book out of my local library. Because Reasons, the library doesn't "own" unlimited "copies" of the book, so each "copy" can only be checked out to one patron at a time and if there are enough holds then a patron can't renew a checked out book. In short, ebooks in libraries are just like regular paper books, except to you don't have leave your house.
I had this ebook on hold for three months because it's very popular, but finally have it on my device, but I only have 3 weeks before I can no longer read it because of holds. I get about 2/3rds the way through before lock closes on the bits on my device. It's a very popular book, it will be 3 months before I can read it again.
I go online, use some service, find the exact same book, down to all but the locking bits, and download it, finish reading it a few days later, and then forget about it. I might delete it later if I need room.
Is that a crime? Have either the author or publisher lost money? On the one hand, I can say yes because if the libraries purchased more "copies", the waiting list wouldn't be so long, I might have been able to renew it and finish it. On the other hand, I wasn't going to buy the book myself, and the library has to balance budget and demand, so they probably wouldn't purchase additional "copies".
What ethical questions do authors and readers see here?