Are you imagining something different from a well-appointed apartment complex?
I live in one, it's very convenient, and I could probably avoid ever leaving if I wanted to,* but I don't think it bears much similarity to a leaking, lightless slum. And it couldn't while being managed by laws (specifically, building codes).
* I work from home, but there's plenty of employment to be found within the complex too, including a few office buildings.
I looked at purchasing a condo in North York up in Ontario a few years back. The condo was connected to a shopping center with grocery, restaurant, movie theatre and other shops. In addition it was right on top of the subway station. At that time I worked downtown in a building also with direct access to the subway as well as to the PATH network. So in this scenario I literally could never go outside and get everything I need, which is both good and bad.
I guess I had something like that in mind but minus the subway so things are in a smaller radius.
I live in one, it's very convenient, and I could probably avoid ever leaving if I wanted to,* but I don't think it bears much similarity to a leaking, lightless slum. And it couldn't while being managed by laws (specifically, building codes).
* I work from home, but there's plenty of employment to be found within the complex too, including a few office buildings.