That is a very profound point you’ve just made - it made me think.

While I think you’re 99% correct, I think there is a serious counterpoint to:

A difference in beliefs … can be addressed through the inspection and sharing of evidence

This can only be true if both hold values that make logic/reason matter more than emotion or nihilism/postmodernism.

Some people have fallen into the trap of emotionally rejecting other people’s arguments and denying what are self-evident facts (if you accept realism is basically true). By denying a shared reality, it is near impossible to jointly reason in the space of beliefs about reality.

Sadly this is important because the right has spent about 40 years denying basic truths (like trickle-down economics doesn’t work and children dressed as cats have litter-boxes in liberal schools). In the last 10 years or so they have developed a complete alternate reality on the Internet, and the single most important facts in this reality are that mainstream media is lying, there is a giant conspiracy controlling the governments and science and that the best way to find the truth is to do your own research.

Their pride.

The EU and US standards are very different and products for one can’t necessarily be shipped to the other and vice versa. Examples for food include massive differences for colourings, preservatives and the like. Europe will not accept chicken washed in chlorinated water or bright froot loops. Health traffic lights are also going to be different.

While it’s possible to have 2 production lines, 1 for each economic zone, that’s expensive for producers and shippers.

A full renegotiation of the US Canada trade border would be chaos

But that is precisely what Trump is demanding now. Even though he tore up NAFTA and renegotiated the deal in his first presidency (I am sure I remember him saying it was the greatest trade deal ever signed and the greatest win for TrumpAmerica).

They don’t need to join it as a full member to have trade and economic benefits. Simple (!) alignment with standards and regulations will allow free access to the market and free movement of people.