There is a surprising phenomenon in microeconomics called the Alchian–Allen effect[1]. Quoting from Wikipedia, "[W]hen the prices of two substitute goods, such as high and low grades of the same product, are both increased by a fixed per-unit amount such as a transportation cost or a lump-sum tax, consumption will shift toward the higher-grade product. This is true because the added per-unit amount decreases the relative price of the higher-grade product." The quality of Japanese produce could be due to the effect of the higher prices on consumer decision-making rather than any advantages of small-scale farming.