The farmer owns the farm and benefits directly from the improvement in operating margins. A software engineer does not own the farm, only the owner would benefit from improved productivity. They're actually getting paid less per hour given they're more productive in this hypothetical.
I grew up in a family with a lot of farmers and I can tell you this is not universally true.
It’s very common for farmers to have leased their farmland or fields.
I can also say we are all very much better off with farming automated on a large scale. Farming jobs were brutally difficult in the past
Productivity really is good for everyone. It’s the reason quality of life has improved dramatically in the past 50 years despite real wages being stagnant to declining.
During WW2, the Japanese would take several weeks to make an airfield, using a large labor force with picks and shovels.
They were horrified when the SeeBees showed up with bulldozers making forward airbases operational within hours.
And maybe it happens to software engineers next. So what? The economy looks completely different today than it did 50 years ago, which was completely different than 50 years before that, and that shouldn't stop just because some people feel childishly entitled to do the same work for their whole lives even it if it is obsolete. I'll just change careers like I have done twice before. There's a massive shortage of electrical/plumbing/hvac contractors. There's a massive shortage of nurses / doctors that will only get worse as the population gets older. Not as cushy as my mid six figure tech job, but I have no god given right to that. And there's plenty more opportunity beyond that for anyone willing to take it, so if any other engineers want to cry about it, their tears will be wasted on me.
Like you said, owning farmland wasn’t as common as everyone assumes. The number of farming analogies where everyone imagines the farmer as operating a lucrative business empire on land they own is a testament to how much people manufacture historical narratives to fit their desired narratives.
I would be shocked if more than a tenth of a percent of people who write code for a living work in startups, period.