All the reasons that anti-immigration people give to limit the number of immigrants into the United States(immigrants take jobs from citizens, consume welfare benefits, use infrastructure, etc.) seem to apply equally to reproduction (above replacement rate, which I believe is about 2.1) by US citizens. Therefore, if you’re anti-immigration, you should be equally opposed to the child tax credit, and favor heavy subsidies for contraception. After all, less children means that there will be less competition for jobs, some of those children might use up welfare benefits, etc.
The kicker is that it’s much easier to control immigration to solve these problems-you could let in high-skill immigrants who are unlikely to need welfare benefits. But absent a reproductive policy even more coercive than China’s One-Child stance, there’s no way to ensure that underprivileged US citizens don’t have children that due to their parents’ poverty are themselves in need of welfare benefits.
Of course, I think that immigrants are a net-positive for the economy (putting aside the obvious humanitarian case for increased immigration). But if you think that immigrants are not a net-positive for the economy, then there’s no real reason to think that more US children would be a positive for the economy. Let’s have an economy of just aging senior citizens! That’ll solve our entitlement crisis.
On the flip side, if you’re a pro-natalist who thinks that we need more youth to help the economy and fund entitlement programs, like I believe quite a few conservatives are, why favor the child tax credit or other subsidies supporting reproduction over immigration? Letting in more youthful immigrants could easily smooth over the demographic curve that we’ll be faced with once the baby boomers retire.
Perhaps I am a cynic, but I suspect that people avoid the obvious solution of more immigration to help the economy because of nationalism/fear of the other.