Farming automation and the green revolution didn't make us all unemployed - it meant 90% of us could do something else instead of farming.
We used the productivity to just invent new forms of work that weren't possible and aren't possible in a lower productivity economy.
There was actually a lot of fear that there would be mass starvation and competition for food because food production could not match population increase. It was an existential threat, much like how we look at global warming. And that fear today? Gone, and most people never even knew it existed.
What actually happened in agriculture is that technology enabled massive conglomerates to dominate the industry. I see few guarantees that technological progress is going to free me up to do something else that enriches my life.
I have a hard time believing you believe that most people switched to a worse paying job. Did peoples material quality of life improve or not?
I think unionization would impact expansion and research areas —the big bets where now if something doesn’t work the company either reorganizes the team or lets go of a team. With a union companies would operate more conservatively.
That would perhaps provide stable jobs for current job holders but limit growth for prospective job holders.
Everyone who is not a slave, serf, or subsistence farmer