I decide who I want to welcome in my home. I believe Thailand, Russia, Brazil, Germany are completely free to do the same and fix their own rules.
But you don't. Take the US, for example. Everyone born there is a citizen. Everyone born to an American parent is a citizen (or can be). None of the folks get a choice in where they were born, or what nationality they get. And you have all sorts of folks - people that will rape you and your family, and others that will give you food without going through a means check. You don't get to choose what the child next door will become any more than you chose your next-door neighbors.
Yet somehow, keeping out "the others" is giving you a choice? You don't even get real say who they keep out and who they let in. It isn't choice at all, I think.
People don't just come to a new country and just abandon their past. They bring their values, ideals, beliefs, problems and solutions. As the number of foreign people coming, cosmopolitanism increase.
Then you quickly reach a point where you can eat a raclette anywhere, soccer is the most famous sports, Hollywood is the main entity broadcasting entertainment. There is no point in traveling, because every place more or less lost their spirit.
And I am not talking about the fact that, if countries completely drop their requirements based on nationality, they will keep their "usefulness" requirements (who is able to take a job we are looking for)
What's going to happen? Well educated people are going to move easily. Further depriving countries of the very ones they need to develop their countries.
It will be a one way street. I don't imagine hundreds of thousands of Americans moving to eastern Africa anytime soon.
People used to say that folks with different color of skin had a different culture, and therefore interracial relationships do not work. People move across the country (in the US) and get culture shock. In other words, people don't really consider others as having the same values and culture. "Contribute to the economy" is a weird phrasing: Most of my family worked to not starve and immigrants contribute to economies as well.
If you are afraid that someone from a "leser" country with a "lesser" value system is going to mess up your life, it isn't and the actual answer is for humans to make sure their global neighbors aren't crappy countries to live in. It is, after all, partly our fault (our = "developed countries") since we rely on the slave conditions in "developing" countries so that we have toys and food.
None of it is a perfect answer, but striving for it is much better than simply reasoning, "I guess we'll just have to exploit these folks". Realistically, that's what we are doing with immigration: Keeping the folks we've exploited the most... out.
This will be nowhere near enough. Maybe 5%.
Less traveling would probably be good for the world, but it's not true that places "lose their spirit" just because they've got football, Hollywood movies and raclette everywhere. They already have that everywhere, and almost everywhere is still interesting and unique. Just more accessible, leading to more travel.
Cultural exchange is useful and valuable. What's a problem is when desperate people have no buy-in into the society. That leads to alienation, which can lead to all sorts of problems. But this can also happen to people whose parents, and possibly distant ancestors, already lived there.
I think the opposite.
It doesn't have to be this way if trust between groups improves such systems could appear. Ironically the ambitions to solve racism did create even more distrust as it seems, but the setback is hopefully temporary.
I don't think a country with strong social security could ever survive open immigration for too long. It would have to adapt and restrict social security because the societal consent has to be reestablished.
I am not from the US.
Open immigration doesn't necessarily mean open rights to social structure: After all, most places have some limits on the safety net you are entitled to now - For example: Taking certain types of social help here in Norway hurts my own immigration. You can have some controls on this: One actual answer is to make sure everyone has basic things as rights (Such as food and shelter) and work on making everywhere decent enough places to live - but for this, we need less global exploitation.
I do agree that we should make sure everyone knows how the systems work in reality, but realistically I'd want to lean into things folks would actually use instead of memorizing dates and names: You don't need to know all the laws, just how they pertain to you. You don't need all government structure, but general and the things you'll probably deal with (local government, motor vehicle laws, etc), what to do if you find yourself disabled, poor, or needing time off for surgery. Making sure everyone knows worker and tenant rights would be a step in the right direction as well, as well as what to do about these sorts of things.
On the other hand, I had practice tests on a computer (at a school). My test was full of practical things and only a little history: Mine asked me about using the health care system and the schooling system and things like that - the sort of thing that once you learned general knowledge, you didn't have to worry too much if you couldn't remember a historical name or date. I took the civics test required for Norway, by the way, and they have a list of languages you could take it in. Of course, I had to take it to continue my residence so more folks wind up taking it.
Edit, forgotten thing: Whether or not someone is stateless depends on the home country, but generally, it won't - mostly because the US doesn't make you give up citizenship before you are granted on in the US. If you want to become a US citizen, though, your citizenship is going to depend, in part, on this civics test. This is what I was referring to.
https://www.uscis.gov/citizenship-resource-center/the-2020-v....
What is insane about it?
"You don't need all government structure"
Sure, you don't need to know everything. But it sure helps if people understand the role of the three branches, how laws are generally structured, etc. You might be surprised by how many people can't name the three branches of government or don't understand their role. In my opinion, that will eventually lead to abuse/changes of powers such as we see with the federal executive branch usurping powers it never originally had over the past century. It's hard for a citizen to see when rule of law is bypassed if they don't know the rules/structure/purpose of the system.
I took a civics test for Norway. I had a 6 week civics class, and they try to give the class and the test in a language you know. Mine was in English, as was my test (I'll have to take it in Norwegian before citizenship, as they changed the rules).
Most things on the test were very practical things indeed. No need to, for example, memorize every political party that is on the national ballot, for example, and only a question or two (tops) that wanted a historical date at all. The vast majority asked things about the health care system, schooling system, and basic useful things like that. The class added more detail, but they tested basics. The test is electronic, taken at a school so it is secure (no bags/phones at your computer, for example). I could get on a government website and take a practice test, too.
I'm American. The american test is more concerned with you learning the propaganda of the country and memorizing dates than it with making sure you can navigate different systems in society. "Topics about government and history", they say. The actual website states, "Although USCIS is aware that there may be additional correct answers to the civics questions, applicants are encouraged to respond to the questions using the answers provided below." [1] They aren't testing how well you can navigate the system or things you'll need to, say, drive: Hence, insane.
Though admittedly, it is shorter than I expected: They only ask 20 out of 128 questions (mine was 30ish) - and you only have to get 12 right. Unfortunately, it is also oral, so (for me) it would be much more stressful, especially considering the brutish formality that a lot of American institutions have.
[1] https://www.uscis.gov/citizenship-resource-center/the-2020-v....