And of course, a lot of Canadians mostly look and sound like white Americans, so we don’t think twice about them, but Mexicans look and sound different, so it’s easy to rile people up about the “invading foreign culture” that will “destroy America.”

The echo of America's original sin still dwells in the heart of every American. Deep down, there's some primal fear that what we did to others will be done to us.

two countries

If we count all the bases, USA has more countries bordering its land, than any other.

I dunno, I think it makes more sense to compare the US to the EU than to individual European countries, given that European countries are more the size of US states.

Many state communists oppose open borders. The USSR, China, and Cuba all had/have citizenship privileges and controlled migration, and generally people that support those governments are also called "leftist".

The same goes for many social democrats and socialist reformists. Even unionists often oppose migration because migrants are imported by the capitalist order to use as scabs (see "guest workers" in 1970s West Germany).

All basically want a walled garden in which leftist ways of living can flourish, usually with the idea to export them later.

But especially in activist and discourse spaces, people tend to be in a pretty narrow band from pop liberalism to anarchocommunism. Socialists, socdems, and unionists tend to be busy with their job, because that is what their praxis calls for. And state communists tend to walk away exasperated when people condemn genocide.

But anarchocommunist praxis is for a large part prefigurative sharing of information, ideas, and tentative structures. So we're relatively loud and as unemployed as we can get away with.

Exactly. Being a migrant isn't exactly a picnic. I think it's reasonable to assume most people would like to live near their families and homes if that's a viable option. I still think people should be able to go anywhere in the world if they want to, but they shouldn't have to. A lot of the "problems" of immigration are just the point at which other people's problems become inconvenient for me. If we can make the whole world a nice place to live, we'll be well on our way to making borders not matter so much.

and once they've eliminated that enemy they need a new enemy to eliminate

There's a difference between serving the oligarchy at large and personal loyalty in a cult of the personality.

It's much harder to get citizenship in most EU countries than it is to get citizenship in the USA. Until Trump, it was also easier to get into the US on a visa than to get into Europe on a visa.

I think I've seen border checkpoints while driving between EU countries, but it was hard to tell because they hadn't been in operation for decades. But, there's still a vague sense of a border. It seems like the countries maintain that area enough so that if ever they had to put the border control points back into operation it could be done. So, you can sort of tell that you crossed a border, even if you don't have to slow down at all.

I seem to remember that the USA was part of the model when the EU was being designed. That doing business between EU member states was supposed to be as easy as doing business state-to-state in the USA. It isn't quite there yet. But, the USA has been working at reducing state-to-state friction for nearly 2 centuries, whereas the EU has only had decades.