The Department of Homeland Security has helped to bust a "large scale Canada-U.S. cheese smuggling operation," NPR reports. The idea was to sell in Canada cheese from America, where prices "are anywhere from a third to half what they are in Canada."
Any time there is such a dramatic price difference it's a good indication that government interference in a free market is involved, and sure enough, the NPR article makes reference to "import duties" that are in force to protect Canada's dairy industry from foreign competition. It may be that American farm subsidies are keeping prices artificially low on this side of the border, too. (An earlier article here reported that the American government decided 50 years ago to subsidize cheddar cheese, but no other kind.)
It's amazing that nearly 20 years after Nafta this kind of nonsense persists. It's also a useful reminder that whenever and where-ever government-imposed price differences exists, entrepreneurs will step into the breach, legally or illegally, to try to arbitrage the differences.
The NPR article treats the matter somewhat humorously, with references to a "mozzarella mafia." But if you're a Canadian paying extra money for pizza, or an American whose taxes are going to subsidize cheddar, it's not a laughing matter.