Seems unfair to predict with onions, when the onions themselves are exempt from being predicted

https://www.good.is/articles/the-great-chicago-onion-ring-wh...

As I understand it, the problem with perishable goods is that any regulation can only protect one side of a futures market or the other, so if you want to treat both sides equally the Solomonic solution is not to have them.

And yet milk futures are traded on the Chicago Mercantile Exchange.

https://www.cmegroup.com/markets/agriculture/dairy/class-iii...

Here, dairy is stocked and sold without refrigeration, but that's probably not true in Chicago.

Maybe the difference is that new milk arrives twice a day, whereas onions are annual?

Lagniappe: https://www.youtube.com/watch?v=yW-n0DJFalY