Sounds like they need rules that state you are only allowed in if you actually want to use the library for its intended purpose.

What do you think is the "intended purpose"? The fascinating and beautiful thing about the library systems in US is that there is no reason to have a purpose, you can literally just sit down and look outside the window. Breakneck-speed-modern-life needs this. I want a place to stop, think, read, write, listen... just somewhere to be human without fees for a second.