"Just get a roommate" is not always an option. This applies to lots of other "obvious" solutions people like to come up with when it's not them.
It is not common in the US because there are aid programs for people with children that suffice to let them get private housing, and at the very least pay for their childrens food.
It's not an interesting "simulation" because it's effectively just stating that you can run your life into a corner if you don't pay attention.
I don't mean to put words in your mouth or assume what attitudes lie behind your personal thinking, I'm just reflecting on my own thoughts about this.