University libraries at larger unis are usually open 24/7 or at least extended hours

Those do exist! A few libraries in the Netherlands have a system that basically gives patrons a key to access the library even when it was closed. Basically, you’d hold up a keycard, building would open, lights go on, you grab a book and check out and walk out the door. Lights go off, building locks itself.

Wild, right? That only really works in a high trust society of course. They reasoned that avid book readers don’t steal and that thieves don’t read.

Usually they limit it to something like 7 AM to 11 PM, so there is SOME limit to it, but that certainly makes them more accessible to those of us who work.