Oh, I'm in Vietnam. I've been here about a decade. It's true that the 'slums' here are quite nice, I live in one of them. It's safe and pleasant, if a bit crowded. 80% unemployment is about right for my area, but mostly people don't seem to feel the need to work -- too much trouble for too little money. I mean, they're going to get priced out of their own homes in a generation or two, but I admit that they lead happy lives!
Unofficial dwellings are common, but usually take the form of an unregistered dwelling, on land legally owned by the residents. This lets them informally subdivide plots as families grow.
Most families seem to own the home they live in. I don't know all the details, but it is sort of de jure impossible to be homeless here. I think all families were allocated a piece of land at some point -- I don't know the exact mechanism (since I immigrated here long after that was sorted out). Then you are registered in the 'house book' for that land, and have some claim to it. I've never met anyone whose family doesn't have at least one piece of land they can live on, even if it's far away.
In practice, someone could have sold their plot, it could not be a good enough piece to live on, it could be far from an economic center, too many floods, and so on. There are de facto a few homeless people.
If your land is out in the countryside? There are some good things about that, too. Not many economic opportunities, but you're also not going to starve. It's not like Canada where you need a ton of civilization just to survive. Want food? Walk to the nearest fruit tree or go fishing for an hour. Some of my colleagues in tech are tempted to just give up and go back to their hometown instead of doing this ridiculous hustle.