And except for Argentina, Brazil, Canada, Chili and Uruguay, the rest aren’t what one would think of as “sought after”, otherwise you’d have other people trying to take advantage of their citizenship policies.
I’m not pro jus soli but to characterize birth tourism as a big problem is crazy. A conservative think tank estimated it at 40,000 births per year out of 4.3 million (0.9%) — the average delivery costs $32,000 for an economic benefit of $1.28B per year. Then those poor kids are going to have to pay US income taxes for the rest of their natural lives no matter where they live. We can expect the first 18 years to be abroad since their parents don’t get citizenship and the US has effectively zero social safety net anyways. What’s the big deal?
So, no, we still would allow millions of legal immigrants in. We’d just crack down on unregulated immigrants.
Said countries have even laxes immigration policies, similar proportions of immigrant populations, the same anti-immigrant rhetoric that you're spouting, and yet it's just not really the problem that it's made out to be at all.
Chile is also cracking down on illegal entries now that they’re more prevalent. No country will have unrestricted immigration, otherwise why not form a union with neighbors?
Also my claim wasn’t false as you suggested.
Also, I’m for immigration where we have proven needs. I don’t agree with flooding the market and depressing wages for average workers. PhDs, sure, rare skills, sure.
Or, let’s put it this way, would you be in favor we took Japan’s immigration system part and parcel and implemented it as they have?
The United States puts American workers at a unique disadvantage to immigrants because there isn't much of a social safety net. It ends up a race to the bottom for cheaper disposable labor.
See: The European Union
Inb4 "Yeah, but they have immigration control," yes, they do but upon entering and leaving the Schengen; otherwise, it's based on agreements with other countries.
It's why you can travel to Europe for up to 90 days on only a "visitor" visa (which is, really, just an entry stamp).
...but to say that countries don't trust their neighbours have strict border control between themselves (and haven't formed a union with their neighbours) pretty much negates the realities of the Eastern hemisphere.