Pretty piss poor reasoning there. Both oil and corn production and demand far exceed onions by a significant order of magnitude. Saying onions are more volatile than corn is like saying that the fortunes of individuals are more volatile than those of society at large (i.e. basic probability theory). Both corn and oil are more diversified than onion - and in turn - exhibit a lower variance - futures market or not.

Global onion production: 74,250,809 tonnes/year (2012 - http://en.wikipedia.org/wiki/Onion#Production_and_trade)

Global corn production: 817,110,509 tonnes/year (2009 - http://en.wikipedia.org/wiki/Maize#Quantity) (10x onions)

Global oil production: 84,820,000 barrels/day (2011 - https://en.wikipedia.org/wiki/List_of_countries_by_oil_produ...) -> 4,923,850,000 tonnes/year (70x onions)

I'm surprised onion production is that high. Corn is in so much stuff (And as far as I could tell while there, is in all US food) while onions aren't.

Corn is in so much stuff because it's production is subsidized by our government, and therefore is much cheaper to use than alternatives. This is why you see high fructose corn syrup used to sweeten foods more often than regular sugar. Sugar is (for the most part) imported, and sells at a much higher price than our subsidized corn products.

Also, the government artificially inflates the price of sugar, otherwise it would be even cheaper than the current price of HFCS: http://dailycaller.com/2012/12/03/sugar-tariffs-sweet-for-sp...