Some thoughts about that:
1. In the US, zoning laws discourage building things like the "mother in-law suite". These zoning laws were originally created as a way to get around federal laws prohibiting discrimination of race and sex by making it more difficult for people who can't afford housing to live within a certain neighborhood. Even if US residents wanted to add housing for some semblance of independence, zoning laws makes this difficult.
2. In the US, children are educated to become factory workers, and inegunity is deliberately suppressed. (See John Taylor Gotto's The Underground History of American Education).
3. When I look at Carol Sandford's work on regenerative business and regenerative life paradigms, I realized that people here in the US have been conditioned to think that being able to live independently is the mark of an adult. But that is an illusion. They are still largely treated like cogs, whether those are adults who are working full time jobs, or children in the compulsory school system.
4. In contrast, a regenerative business builds up the capability for each employee to figure out what they want to do that will make a meaningful contribution to the business and society in a way that aligns with the general direction the organization is going and the general strategy. Being able to do that gives a far greater sense of fulfillment, purpose, and agency to the people involved. It's as if every employee has the chance to be a mini startup within a larger organization, and the organization as a whole become more adaptive, resilient, without sacrificing being a responsible corporate citizen.
5. When I think about how that is applied to children, I am reminded by the NPR article about how indigenous families have children doing chores without resentment. (https://www.npr.org/sections/goatsandsoda/2018/06/09/6169288...) ... and then I realized that, it isn't really about chores. It is a way that children from indigenous families are encouraged to make meaningful contributions to family and community from a young age.
6. If your sense of self-worth and purpose is derived from making meaningful contributions to the family, community, and society, you're no longer pidgeonholed into the role of being a child. As such, I think a lot of the tensions and inter-generational drama we expect from adult children living with their parents is no longer there.