It's (to some extent) a Nordic thing.

http://appsso.eurostat.ec.europa.eu/nui/show.do?query=BOOKMA...

Thanks for your comment, and that of others. It appears that my culture is the odd one out where flatsharing is viewed very negatively.

Sure, it's not non-existent, I have many friends who have done it at some point in their lives, but it was always with existing friends. Advertising for a roommate, i.e. inviting a stranger to share your place is very unusual.

People's expectations of privacy are simply much higher.

The cheapest form of housing for college students is one where you share a kitchen and a living room with a bunch of other people, but everyone has their own private bedroom and bathroom with a door that locks. College dorms is just not done.

It is possible to rent a room in someone else's apartment, but usually in that arrangement the apartment is built such that the part that's rented out is a bit more off, has it's own bathroom, and has its own front door.

Yes, but when Americans (e.g. college students) talk about "roommates" they mean they share a bedroom! Literal roommates

As an Australian in the US, it seems that term is ambiguous.

When a college student talks about their roommate, yeah that's the freaky situation of being an adult and not having your own bedroom.

But on other contexts it just means what I would call a "housemate". You're not actually in the same room.

This is not true. Sometimes it refers to this. The vast, vast majority of the time, they are referring to someone who has their own room in the same apartment. Source: I had "roommates" in the way you refer to it in college, and after graduating, most people who I describe this to are actually shocked that this happened after freshman year.

Nah, that's pretty exclusively a college dorm thing, where it has a pretty direct relation to the price of the dorm.

(my uni had both twin and single rooms, and the twin was maybe 60% of the price)

Only in dormitories. Roommates in an apartment don't normally share rooms.

We don't. I'm an midwestern american college student and "roommate" means "someone that shares your living space" whether that be sharing a room to sleep or just sharing kitchen/bathroom/living room space. The only alternative I've heard is "suitemate" in suite-style dorms.

That's not true. Roommate almost always means two people sharing one apartment with their own bedrooms. Dorm-mate, on the other hand, specifically means two college students sharing a dorm room with two beds.