It comes from a very particular age.

It was after WWII when the US was one of the few countries that hadn't had its infrastructure destroyed by the war. It was also the late 1940s. In the 1930s the New Deal had shifted a lot of power from the rich capital owners to workers, but because of the waning years of the depression and then WWII, nobody had really seen the fruits of that work. Suddenly in the late 40s, the war ended, the US economy was in a huge boom because it was the only place in the world that could still make things, and workers had all kinds of hard-won protections.

This was never going to be sustainable. Eventually the rest of the world was going to rebuild, which was going to result in more competition, and a relative weakening of the US economy. But, the post-war years also saw union power getting weaker and weaker. A significant part of that was that organized labour smelled a lot like communism, which was the scary enemy from the end of WWII to the 90s. So... no communism, no organized labour, nobody to push back on the rich as they consolidated power.

Also, inflation isn't really the issue, it's that workers don't have the power to demand that their wages go up as well. And, of course, with so many workers supporting an anti-union, pro-business party like the GOP, worker power is going to stay near zero.