I don't understand what is funny here. Many university librairies are open until 9 p.m and there is still people at the closing that would stay later. If every librairie were open until 10 p.m or midnight, you can be sure that some people would make use of it.
Idk how it works in your country but where I am, anyone can access a university library and many students also frequent the public library. So basically, if every library were open late, anyone could go to the library of they choosing.