My comment didn't speak to the pre-WWII era, but going back to the nineteenth century, the U.S. has always had a robust workforce more-often-than-not offering opportunity for upward mobility for those motivated enough to take on the work. What's significantly different now is that we have a much bigger safety net for the retired, young, ill and disabled.
But what's also different is the very recent lack of upward mobility. People born after the 70's are coming in behind their parents unless they inherit land or equity holdings. Does a worker stop paying rent to a landlord in order to build that "nest egg" as you admonish them to do so? It's hard to save for retirement when the landlord keeps coming back every year with a $300/month rent increase - because they can, because every landlord is doing it, and because elected officials and courts give them cover to do so.
But what's also different is the very recent lack of upward mobility. People born after the 70's are coming in behind their parents unless they inherit land or equity holdings. Does a worker stop paying rent to a landlord in order to build that "nest egg" as you admonish them to do so? It's hard to save for retirement when the landlord keeps coming back every year with a $300/month rent increase - because they can, because every landlord is doing it, and because elected officials and courts give them cover to do so.