The big change is the end of any sort of backing in money. The Minneapolis Fed calculated consumer price index levels since 1800 here. [1] Of course that comes with all the asterisks we're speaking of here for data going back that far, but their numbers are probably at least quite reasonable. They found that from 1800 to 1950 the CPI never shifted more than 25 points from the starting base of 51, so it always stayed within +/- ~50% of that baseline. That's through the Civil War, both World Wars, Spanish Flu, and much more.
Then from 1971 (when the USD became completely unbacked) to present, it increased by more than 800 points, 1600% more than our baseline. And it's only increasing faster now. So the state of modern economics makes it completely incomparable to the past, because there's no precedent for what we're doing. But if you go back to just a bit before 1970, the economy would have of course grown much larger than it was in the past but still have been vaguely comparable to the past centuries.
And I always find it paradoxical. In basic economic terms we should all have much more, but when you look at the things that people could afford on a basic salary, that does not seem to be the case. Somebody in the 50s going to college, picking up a used car, and then having enough money squirreled away to afford the downpayment on their first home -- all on the back of a part time job was a thing. It sounds like make-believe but it's real, and certainly a big part of the reason boomers were so out of touch with economic realities. Now a days a part time job wouldn't even be able to cover tuition, which makes one wonder how it could be that labor cost practically nothing in the past, as you said. Which I'm not disputing - just pointing out the paradox.
https://www.minneapolisfed.org/about-us/monetary-policy/infl...