> This is only true if we are only talking commodity crops. But the average farm in the us is still only ~400 acres.

This metric is misleading because of how it's calculated. Since you're weighting each farm equally, a 1M acre farm gets the same amount of weight as a 100 acre farm. Therefore, if in a country you have 100 acres of farmland in total, and the farm sizes are 90, 2, 1, 1, 1, 1, 1, 1, 1, 1, you'd end up with an "average" farm size of 10, but in reality most of the farmland is actually part of a megafarm.