Canada and US have different food and safety laws. Milk is quite a bit different, the laws are pretty strict that US cannot export their milk to Canada. There’s hormones and such the US inject their cows with (in order to produce more milk) that are illegal in Canada. It affects the flavour and how healthy the milk is.

Canada has higher standards of what is acceptable to eat. I believe during covid they did not reduce their standards to meet demands. In the US, if the animal was sick it’s not supposed to be suitable for consumption. But in order to meet demands, they loosened that restriction. Meat quality went down during covid. In Canada the price of meat went up.

The US is also more likely to use fillers and such to cut costs. Like how back in the medieval age, they would cut their flour with saw dust. Basically that. But it isn’t necessarily the law to put that anywhere or what the filler is. There are many products in the US that cannot be sold as that product in other countries. Example: wonder bread can not be sold as bread due to all the sugar. Subway has to be classed as a desert place due to all the sugar, a specific brand of ice cream cannot be classed as ice cream due to lack of cream (and because of all the sugar), so on and so fourth.

It doesn’t surprise me that it’s so different. About 15 years ago I had a burger at a McDonald’s Donald’s in Mexico and it was so different, it was so good. It was like eating at an actual higher end burger joint. The lettuce and tomatoes were fresh, the patties were juicy, the buns weren’t a sweet, wet mess. And it was bigger, too.