And the only people who could afford to tractor at scale are Cargill/Monsanto who bought out most of the small/medium-sized farms while leaving farms that didn't take the offer to slowly die...
And yet there isn't widespread unemployment. Fewer farmers were needed so fewer people became farmers. Food became cheap and plentiful. Everyone else went on to do other things that they couldn't afford to do before. Software will do the same; we will make more software with fewer people and it will become ubiquitous to the point that people will just quickly generate whatever software they need rather than do many monotonous tasks manually.