But it's not just incomes and labour costs. It's equipment prices, it's also land prices, it's land availability, and in North America subsidies for cash cropping favour that kind of farm. But also a huge part it is equipment costs and other costs that favour huge economies of scale here that is not necessarily the case in some parts of Europe, Asia, etc.
Look at what Chinese small farmers farm with -- small nimble walk behind tractors. Now try to get yourself one of these in North America. A BCS or Grillo walk behind fully equipped (rototiller/rotary plow, decent sized engine, cultivator attachment, etc.) ends up being at least $10,000 worth of an investment. Chinese farms are using similar equipment at a fraction of the price (just look on Ali Baba for example. But of course you can't import that without huge tariffs, shipping costs, and regulatory hurdles). On top of that they can get small equipment we can't get here: balers and combines that fit on small tractors or walk behinds and cost little. And they get access to markets as small growers that you can't get here.
Let's say I wanted to get into hazelnut production here. Or buckwheat. Something unorthodox like that that is not soy or corn. I'd be on the hook to not only grow the crop and harvest it and etc. there'd be no market that would take my small amount of crop and pay me for it and process it. To make it worth my while I'd need to grow hundreds of acres and get my own processing equipment and become a large agri corp. And so assume a huge amount of risk.
In places that have vibrant agrarian economies (most of NA does not) and high populations and a diversity of things grown there are more options for processing, etc. A place like Burgundy for example has a huge amount of small wine growers and makers and they form cooperatives and work together to process and market their grapes among a large number of businesses. But the model in North America is far more capital intensive.
