My not so cynical view of the argument would lead me to suggest that "immigration" is an easy and short-term solution to the fertility problem. It's kinda hard to have politicians look at "generational" solutions to problems as the very nature of having politicians is that they "tweak and turn" random knobs to "fix" stuff that we ask them to. The rest is up to us as people and that is why cultural solutions mustn't be discounted entirely and political ones need to support that rather than being full-blown replacements.

I guess my question would be, why try and incentivize people who don't want to, to have children, when you can bring in willing fully-formed adults?

Because it's not always the case that people don't want to have children but they are instead constrained by their situations, which can be alleviated by free daycare, education, healthcare, etc.

I think what you are doing is assuming that the current state of the system is all it can be and that people's decisions they make resulting from the current system what they truly want.

At some point I question why people want to have children if their idea of "raising a child" is shipping them off as early as possible to have someone else raise them. Sure, situations vary, but it feel like these sorts of incentives eventually encourage parents not to parent.

Example of some incentives where I live:

- Pregnant women can start working 6 hours a day at full pay from week 12.

- Up to two years of paternity leave at ~80% pay, capped at roughly 3x the median wage. Either parent can take this, or it can be split.

- 3 weeks of paternity leave after giving birth for the father.

This means a couple can muddle through the first two years of a child's live without worrying about paying for day care of having to quit jobs.

Note that this incentives are country-wide and available for all citizens. The government pays you indirectly while you are in paternity leave.

How does this encourage not parenting?

Broadly that falls under the category of "development" and will have the opposite effect, lowering birth rates, and that's fine. Finland has all of that and more -- in addition to high wages and low inequality. They'll even mail you a box of supplies when you have a child. They have a birth rate of 1.48 vs Canada's 1.5 vs US 1.77

Yes, we should have those things.

No, they won't increase birth rates, they'll probably drive them down. I know it's counterintuitive, but they data is very clear.

Because it is a dangerous fallacy to presume that all peoples are simply replaceable. When you import people you import culture, and that potentially leads to friction.

Don't want to have children or having children has become a much larger economic burden?

I want to understand your argument better - are you arguing in favour of replacement of population for the economic benefits (of who?)?

So why would I - a person living in a country with my own culture surrounded by my own people - want to have adults from another culture with their own sets of values and morals over children from my own people?