I work in the auto industry. You bet your bottom dollar NAFTA has made a big difference. Some parts of North American built vehicles cross the border 7 times before the vehicle ends up in the showroom. Free trade allows someone to build ONE plant anywhere in the free trade zone which supplies the entire zone, instead of having to build three smaller and less efficient plants. That, collectively, gives us a better chance at competing with China Inc.
The BMW assembly plant in Spartanburg, SC builds the BMW SUVs (X5, X6, etc) for the entire worldwide market. BMW cars are built elsewhere (mostly Germany). BMW exports more vehicles from the USA than it imports from the rest of the world (even though Europe is not part of the free trade zone). It still works out better to build all of the SUVs for worldwide sale from that one plant in Spartanburg and all of the 3-series for worldwide sale from another plant in Germany, than to build some of each in each plant. In the next town over from Spartanburg is an enormous Magna plant that supplies all of the exterior sheet metal and a good chunk of the underlying structural subassemblies. That one has kept me hopping ...
My van was put together in Mexico from sheet metal that came from a stamping plant in Italy, a transmission built in the USA, an engine assembled in Mexico from parts that came from the USA and Canada, including an oil pump assembly from a plant in southern Ontario that is also one of my customers ...
As far as beer is concerned, yeah, forcing breweries to have multiple facilities in separate provinces is a make-work project and that's why it has been like that for many decades, but when your competition is "the rest of the world" which doesn't have that problem, it is ultimately a losing proposition.