No one has mentioned the role of recreational drugs in sapping the ambition of what would have been working class young people. Getting anyone under 40 to show up every day for any job is almost impossible.
With the exception of slavery (unpaid labor), the way to get people to work was to entice them with pay. Young people (like anyone else) will work for the right price; our imported “replacement Americans” have plenty of involvement with recreational drugs/alcohol, and they’re still working...