Butter.
No, really. In Canada, the dairy industry is run by a single co-op. That means that all milk and milk-based products must be sourced from the co-op (i.e. your provincial dairy bank).
So all butter in Canada comes from the provincial supply. Want locally-sourced butter? It's nearly impossible to obtain, and even if you can, it's extremely expensive due to tariffs. Want butter that's completely grass-fed? It's possible, but also extremely expensive, and it comes from the provincial bank, so it's possibly mixed with other cows and/or milk. And all butter is 80% milk fat, which is abysmally low. European dairy is 85%, sometimes 90+%.
Only very recently has it been possible to buy "New Zealand" grass-fed butter here, but it's $11 per 1/2 pound, likely due to import tariffs. And it goes through a local dairy, so I'm not 100% confident it's truly New Zealand milk. Nor can I confirm its fat percentage, so I could be just paying for a lot of water.
If you want to drive across the border to buy butter and bring it back, be prepared to answer a lot of questions to the CBSA, and possibly pay more tariffs, making it prohibitively expensive.
This applies to most other agricultural products too, like cheese, eggs, wheat, and more. Getting good cheese in Canada is expensive and hard.
The fact that the article mentions that the CETA made strides in agricultural issues tells me that what I cited above is a possible issue in these trade negotiations. The same was true for TPP.
I'll be really happy when these trade deals pass so I can get some real food at a decent price, and my local farmers can be given an opportunity to compete. Until then, the biggest opponents to these deals are farmers. That should make you question their motives.