You would say it's all based on the market, but poor people don't have enough money to be "in" the market. The market may eventually adjust itself, but not soon enough for these people to survive.
Having grown up row-cropping corn and soybeans, I can tell you that crop yeilds per acre have more than doubled in 30 years and have increased 10 fold or more in the last 100.
There is also substantially less ground being tilled for row crops now than there was in 1970, so I don’t follow with the assertion that available productive land is being consumed.
The market is the market. Stop paying market prices and watch the farmers stop growing corn. Its that simple. The percentage of acres put to corn (vs. wheat and soybeans)is higher now than before ethanol.
Conversely, subsidies for ethanol have perverted the market and corn prices are artificially high. Without the subsidies, corn based food (mainly meat, eggs, milk in the USA) would go down and ethanol prices would go up (likely leave the marketplace). Poor people are well served by a productive market, because without it they starve.