Fun fact, it hasn’t, outside of a handful of sectors: https://aneconomicsense.files.wordpress.com/2017/03/real-val...

Wait. I’m not sure I understand what that chart is supposed to show. Are you suggesting because the GDP is only linearly growing productivity is not increasing?

No, look at the “services and construction” line. That measures output per worker in that sector (2/3 of the economy) since 1947. That’s a measure of productivity per worker. It’s grown at only 0.9% over that time. A big chunk of even that tepid growth is in a handful of areas like finance. In vast swaths of the economy, workers aren’t any more productive today than in 1947. Everything from building houses to caring for kids and old people to serving diners at restaurants, etc. We can make iPhones with fewer workers than ever but the post-scarcity economy is very far away.

I don’t have much of an opinion on the scarcity economy but I think you could read that chart differently. The industries that have listed the longest, agriculture, manufacturing etc have seen explosive productivity growth. So you might predict services are next.