»Library-quiet« gives me a cue: Perhaps it's not about the layout of spaces per se, but rather about the social norms observed by everyone in whatever space they are wring in. A library reading room supports uninterrupted work despite its open layout and the number of people present. The social norm there is to be quiet and avoid any distraction of others. To make a phone call or have a meeting, one needs to leave the reading room and find a place elsewhere, such as the cafeteria. A separate office, on the other hand, can be pretty busy and rich in interruptions if coworkers drop by too often.

As a case in point, I enjoy working during longer train rides. The social norms on train are, at least in my country, similar to those in a library: when a stranger is staring at his computer screen, leave him or her undisturbed. This norm breaks down when I travel with colleagues on a business trip. Unless I signal to them I do not want to be interrupted, they will expect they can talk to me at any time.