If there would be enough demand to pay for it, it would stay open longer.

Libraries aren't paid for that demand though

They could be!

Here's a line from my local library's site:

> Our auditoriums are provided as a public service for use by individuals, institutions, groups, organizations, and corporations for a small fee, when not being used for library-affiliated or sponsored activities.

The libraries in my city get paid by membership. That's not exactly visits, but a correlated proxy.

Also if it would become really crowded they would probably think of prolonging opening hours.

Yeah, I was spoiled by my college town. Libraries open until 2AM, a 24 hour space for students. Even a few cafes downtown open 24 hours a day. Suburb life is mostly fine, but that's one thing I miss most.

Gotta travel 20 miles to downtown for anything resembling night life.