I thought you were going to say it for a minute there - the cultural component that you speak of that I feel is missing in our US culture during the younger years is 'duty'
I was also a mess in my 20s and i had a lot of growing up to do to prepare for kids. Yet. Even after kids, I didnt really grow up quickly enough until kids forced the issue.
Having kids and being responsible for someone else who is solely deoendent on you to have a shot at decent life is a monumental duty. I did not have this imprinted on me and I can see why. Our values today are very different from those of my parents and grandparents, and I think that's the big difference.
Im not sure how we lost that as a culture. Maybe its bad leaders (bill Clinton affair etc), loss of religion, loss of community time due to diminished economic opportunity locally (flyover states, most former industrial towns and even cities), economic migration to large metros breaking family ties, all certainly played a role.
it seems correct to say that duty was the slowly boiled frog in the pan, and it looks increasingly hard for the frog to jump out