Other commenters here seem to say that the culture, if not the modern phenomenon, of children moving out of their parents' homes early is more characteristic of the West (U.S., Western Europe), and not so much places like China, Japan, India (continuation of tradition, less modern stigmatization). This aligns with my experience and what little I learned in school as well. (Yes, N = 1.)

It so happens that this pattern is economically inefficient, and only in our inability to support it does its discontinuation serve as a negative economic indicator. American culture makes it an effective metric in the U.S. Where it's already common for children to live with their parents longer though, such as in India, the original choice could very likely be to stay, which makes the metric less useful.