Libraries are different in that they don't remove scarcity, giving a value proposition for both purchasing the book and the library option, if the books are borrowed out further people are unable to read the book at the same time.
A digital example where there is a balance would be iOS, you don't see big antipiracy efforts from developers because there is plenty of market happy to pay for goods.
The real issue is when a content producer can't make anything at all on their time/ money investment, libraries on the whole have never caused this the way digital downloads may.
Point 1, by this logic, I would be more likely to buy a new DVD release of a movie if the video rental store was currently out of stock of said movie to rent.
I would think people would be with point one, more so with books at a library where the wait is usually going to be longer than a day. That app you liked does support the current logic of most iOS developers, the high piracy lead to higher sales so it's not worth doing anything about. If at some point in the future though the piracy made sales so low as to not make the investment in making the app worth wild then you have a problem.
I use the words artists and content producers interchangeably, I guess thinking in terms of the word artist makes their work sound more unique and valuable than content producer.
A digital example where there is a balance would be iOS, you don't see big antipiracy efforts from developers because there is plenty of market happy to pay for goods.
The real issue is when a content producer can't make anything at all on their time/ money investment, libraries on the whole have never caused this the way digital downloads may.