In the case of oil, it takes a much longer time to develop the resources and build the refineries than the annual cycle of growing crops. The country runs on oil. Farming runs on oil (machines, pumping water, making fertilizer and pesticides, harvesting and delivery to market).
OK, everyone knows that, and agrees, so what?
Are you saying that that makes the oil subsidies OK?
BTW, it takes several, 4 to 10 crop cycles to bring an ethanol plant on-line, depending on the resistance of the enviro-nazis.