The law was originally intended to prevent contaminated foods from entering the United States. In short, their view was too stop someone from going to Mexico (the original target of the bill) and picking up some food which at that point could have been safe, but gotten contaminated. Over the due course of this, Uncle Sam took a swing for the rich corporations and enabled them to transfer foods,as they would have proper "handling", and limited drastically how food could be transferred.
This is how chicken, and other food is imported. I live 2 hours from Canada, if I drove to the border with any kind of meat even a bucket of KFC, it would be confiscated by U.S Border Officials.
Normally, when entering Canada tho, its normally Canadian official, and they honestly don't give a f*ck. You throw a blanket over it and they can't see it, you are as good as gold as they only really look in for obvious signs. Mostly true for the US officials, unless your coming in from Mexico then, as you now potentially have over 100kg of crack stashed in your car xD