@іди-на-хуй-Влад-formerly-known-as-Distraxi Great insights and points.
In the US, the trend has been consolidation over the decades. Since we have so much land area, there's far less necessity to cram small farms into every little valley (compared to 100-200 years ago). Those places that still exist in hilly or mountainous terrain often go with more boutique specialties, like winemaking or raising grass-fed cows, things like that.
The running joke in places like North Carolina or Tennessee (my general region) is that millionaires buy mountain property because it overlooks farmland, but that raises the value of the farmland so much, the farmers sell it to other resort developers...and the idyllic view is gone 🙂
As an analog, I'd be interested in what Japan does -- they're notorious for squeezing every last bit of productivity out of their agriculture. I know that even the small farms in the UK Midlands (where we just visited) were very tractor-dependent, despite some pretty steep terrain. I didn't see an ag plane anywhere I looked. But even there, a lot of them seem to be deriving more and more income from organic farm shops and tourism than simply ag production the traditional way, so maximum yield might not be a priority anymore. Just speculating...off to learn more on The Interwebs!
