It is not about that though. Joining the EU means joining in common political institutions, accepting that EU law is above national law, that decisions on EU law are made together in common political instiutitons. It also means that one can be outvoted by others and still be bound by the result. Most areas (major exceptions being defense and foreign policy) of policy making in the EU are nowadays majority decisions with individual member states having no veto power on their own. Joining the EU is not joining some free trade zone or even some defense alliance, it is half way to joining another country (with the key difference that one can indeed leave anytime again).

It is not so much that Canada and the EU would have that many conflict points it. It is again, the level of commitment. Just because you are best buddies, doesn’t mean that sharing the same bedroom is the next logical step. Unless you are serious about that of course.

“what allies, do the US have any left ?”

Russia and North Korea?

Joining the EU is a committment. It is not only an economic free trade area, it is a political union. It also means “pooling sovereignty”, see it as something halfway to a proper federation. I am not saying that this is out of question regarding Canada but I doubt that either Canada or the EU are really aspiring that.

Insulting? He was threatening with invasion and annexation of territory.

It is a fact that they “could” join. There is nothing in the treaties excluding them if all member states really support that. That doesn’t mean Canada should do that. A stronger aliance bereeen EU and Canada with deeper economic cooperation would likeky be the better option.