No because none of these things have futures traded on a major exchange. Agricultural commodities whose futures are traded on major exchanges are very few. Now of course your question will be couldn’t the same be done with a commodity whose futures are traded, such as corn or wheat.

The answer is it is difficult to say. One thing anyone cornering the market has to consider is government intervention. In this respect onions are perfect. They are merely a condiment. Nobody is going to starve for lack of onions if the rest of the food supply is intact. Thus any government official rushing in to intervene in a cornering of the onion market will look a little foolish and thus think twice about it.

If someone tried to corner the wheat market the government is likely to step in, confiscate his goods and pay him a fair price for his wheat which will be much lower than the cornered price. The cornerer will then lose money.

I suspect the congressman that passed the legislation did his research and talked to all potentially affected parties. I suspect the farmers and ranchers producing the other traded commodities said that this was not really a concern for them and that they would prefer that their commodities continue to be traded.