A food cartel is impossible. Just about every single person in the world can undercut such a cartel by growing their own food and make themselves rich selling at a lower price. A oil cartel is not that different, its very hard to keep prices higher than the market would set them. If OPEC charges to much, the producers outside selling for less will make big profits. No one would pay OPEC high prices when they can get it cheaper. Also even if OPEC controlled every single drop of oil. They still could not set prices much higher than market price. One country would fall out of line and sell at a lower price on the black market because that way they would get a bigger slice of the profits. Also even if one person owned all of the oil in the world he could not set prices much higher than market prices because, there is always alternatives. People can always grow oil. In Brazil much of the fuel that drive their cars.. is made from sugar. The price of fossil fuels can never go higher than of grown fuels.
I think OPEC has been kind by selling its oil below re-production price. their reserves are not renewable.. so they should charge a high price for it. I think they should charge as much for it as it costs to grow natural fuel. But they are nice enough to sell it for much less. They are in effect selling it below reproduction cost. Thats no way to run a business. We should thank them for this charity by sending them, a thank you letter every Christmas (okay, maybe not at Christmas).
Cheers