And in some zoning designations, this is actually illegal. For example, years ago I lived in a house in the same town with 4 other guys, but it turned out the maximum number on non-related people allowed in a "single family" dwelling there was 3. The landlord let everyone move in but eventually threatened to kick us out on those grounds.

Things might be different in the States or elsewhere.

But just because you lucked out doesn't mean that it's just as easy for someone else, in another area. To actually create something like this on purpose, somewhere close to where you happen to have gotten a good job? That is hard.

6ren is right, but it's not the whole story. In addition to to being able to have multiple people each entirely responsible for a single lease, we (Australia) have a very generous "student allowance" scheme for most students. This guarantees us students a fortnightly income that is almost certainly at least whatever we would be paying in rent + utilities.

My situation is such an example. I live with three other students and one adorable puppy in an expensive city (Brisbane, Queensland - Numbeo.com estimates Brisbane's living costs as ~87% of NYC's). We live just ~5km or ~3 miles from either of the two local universities, and just above 2km or ~1.5 miles from the CBD. Rent is not cheap in our area.

Yet we had no insurmountable problems obtaining a lease. Rental applications are competitive in this area, so we did have to apply for a lot of leases - but credit concerns were never a problem. Despite being employed for maybe just 12 hours a week each, money is not in question - there are four people each entirely responsible for the rent who are guaranteed social benefits that amount to at least enough for their share.

Unemployed Australians also receive similar social benefits provided they keep applying for jobs.

Youth Allowance with Rent didn't cover my rent in a share house, or even bills. When I didn't have more than one part time job I was relying on money from my Mother to pay the rent.

Realestate.com.au affords some pretty nice share housing at that rate.. :) I admit it's not the standard of housing that I grew up in, but why would I be entitled to such? ;)

But try it in a non-university town where non-students vastly outnumber the students? I don't think so. The landlord has everything to risk and nothing to gain by doing strange and unfamiliar things. If they have even heard of the practice, it's only for students, in student-dense areas, in housing long used in this way, with all the features (internal locks for each room, etc.). Why would they risk their nice house when they can just rent to somebody else?

Rents are expensive. It makes no financial sense to live by yourself.

Even in my home town - which has no substantial university - it's generally assumed that if you rent and do not have dependents, you almost certainly have housemates.

I wonder if this acceptance will keep once the economics changes?

It's like standing on one leg; if that leg crumbles, you will fall and land hard. But if you have two legs, one leg can crumble and the other gives you enough time for you to land gently. If you... magically had a third leg (and weren't standing with them in a triangle?), you might not even notice that one leg stopped working.

Houses there are so cheap that this kind of plan would probably work as long as you had enough human will and intention to make it happen. As far as I can tell, that is where these things break down. It's hard for groups to form this kind of collective dynamic and trust in the absence of some cohering force - religion, a focal point like a cult leader, or similar influences.

[1] Well, OK, two syllables.

There are some cool people who are broke and want to live communally, but there are also some people who do that because they don't have their lives together.