Xenophobia and racism, mostly. And yes, it’s a solution to the aging demographic crisis many countries face (at least in the medium-term).

I remember seeing a video of a presentation back in the Bush years by some neo-con group that advocated for immigration to Pentagon or DoD officials or something. The argument for immigration was mostly the same: we have an aging population, so we could integrate immigrants (who are statistically younger) to solve this issue. I didn’t agree much with the broader idea of the presentation though. The broader idea was that there were still some parts of the world not a part of the global U.S.-led hegemony (mostly the middle-east and Africa), and we must spread democracy and capitalism to them. The argument was that globalism/capitalism ensures peace, and that both WWI and WWII happened because globalism was falling apart shortly before those wars. So, to ensure world peace, we need to globalize the entire earth and bring all countries into the the U.S.-led hegemony, even if that means starting wars to spread democracy, lol.

The birth rates are low because of the terrible environment that doesn’t support having and raising children. All you’re doing is importing more people who will also barely have any children within a generation or so. Mass immigration is just throwing bodies at the bottom of the pyramid scheme. You can see this in action in Canada where housing is absolutely unaffordable, but large numbers of immigrants are brought in who have to work for shitty wages and live with multiple families in a single rental unit.

The screaming about low birth rate is because corporations want to keep a high labor pool so they can drive down the price of labor while keeping up demand for consumption.

Why would you voluntarily create a job scarcity in your own population? Immigration reduces wages, increases prices, strains public services and causes overall decrease in Quality of Life.

Just look at the state of the USA with 28% immigrant population.

Because people fear having their culture and race replaced by immigrants. Even if they’re not overtly racist, few people wish to become a minority in “their own country.”

The US is famously a melting pot, and yet we still have a bunch of descendants of white immigrants from Europe who fear that South Americans will take over; that Mexican culture will replace good old-fashioned hodge-podge Western European culture. That their language will become less dominant. That they’ll find themselves strangers in their own country.

It’s usually an indistinct fear. It seems obvious from the verbiage in the dog-whistles, but white European immigrant descendants don’t want to become second-class.

Now, if we treated our own minorities well, they wouldn’t be so afraid. They wouldn’t be afraid that they’d be the ones with Hispanic cops kneeling on their necks; or that Hispanic immigrants would be living in giant homes and they’d themselves be the ones having to eak out a living as seasonal workers.

I think it’s not despicable to want to preserve your cultural heritage, your cultural language, and to have your country legislated with the values you grew up with; but people react poorly when they think it’s happening.

What I most despise in the Republicans in the US is that they’re advocating for preserving cultural values that never existed broadly in the US. The closest subculture to what they’re pushing is a return to the Confederate South: religion, and white supremacy. The Confederates got their asses handed to them, but the racist fuckers never gave up their values, most most Americans are blind to what their real agenda is. And they’ve been good insurgents, cleverly taking advantage of weak areas in our democracy to return power to a minority: themselves. It’s been said and it’s true: if America was a true democracy and we selected leaders by popular vote, no Republican under their current platform would ever be president again.

Anyway, getting back to your question: immigrants bring their own culture with them, and very few completely abandon it and adopt the culture and language of their new country. This dilutes the host country’s native culture, and people are afraid of that. In the US, it’s the highest form of hypocrisy, because our native culture displaced the indigenous culture, and now we’re afraid of someone else doing the same to us.

Fear of being outnumbered by immigrants (“they shall not replace us” bullshit) is a big one.

Countries like Korea don’t have a cultire of welcoming people from outside and therefor you would have so many clashes that a huge number of imigrants - which is needed - would destroy the country. There is no one here who knows how to treat and integrate those immigrants. There are no programs for them, etc. and even if you know the language you still have huge culture clashes.

A lot of Europe did so and for this exact purpose. Immigrants are net contributors of tax money and help a lot with demographics. Now however European countries have a sizable portion of their countries as immigrants and it turns out a lot of people feel like their culture is getting lost.

Add that up with corruption is more out in the open, austerity after the 2008 financial crisis generally failed as a policy and people are very prone to believe “Immigrants are to blame” and vote for right wing parties since they run on an anti-establishment platform.

The left generally believes that we need more immigrants and more social programs and so on but there has been a massive crusade on tax rates which hinders the governments ability to pay for them.

This is all coming together now and the far right narrative is being given a chance in Europe with their anti-immigration stance.

In my opinion this is basically the centre-right trying to get votes by cutting taxes, end up taking on massive debt or gutting quality of life social programs so the only way forward is to fuck over minorities and making the most vulnerable people suffer for the greater good. But tax the well-off, rich, wealth, land, capital gains, profits? Nooooo, can’t do that because they fund the political parties. 🙃

Why should they? How about we just accept that a shrinking population is the best way to keep the earth sustainable?

Japan sure doesn’t have enough land to sustain everyone without global trade. When that global trade ends in a few years due to global food shortage, Japan is cooked. Better to reduce the population as much as possible until then.

Because most low birth-rate countries are first-world countries, and they generally want to only accept people who can contribute to their society and not be freeloaders to the social system. This means they need to filter out the people that come in, and being first-world countries, there is no shortage of people trying to get in. Sometimes they want low-skill, not-highly educated people just for the cheap labor, but not the person actually staying permanently, hence temporary worker visas. If a foreigner really wants to stay permanently, they then need to ensure that you are educated, able to support yourself long term, do background security checks, and make sure you agree to integrate as you mentioned in the OP.