Children have been seen as the route to happiness. Maybe that never was true.
Until relatively recently, children were what economists call “producer goods”. Children produced more value for their parents than they consumed.
In the past, rural couples needed them to work and provide for old age. The more children, the higher the standard of living.
When families left the farm, and children could no longer work in factories, children became consumer goods. Now, they consume more than they earn. They have to compete with other consumer goods.
One thing that seems to have changed in the last few decades is the increase in unavoidable costs. These are costs of raising children that might have been picked up by the taxpayer a generation ago, Internet, phones and extra training or lessons.
These costs are not, of course, discussed outside the family when contemplating the number of children. It is impossible people don’t know about them and take them into account.
The U. S. fertility rate is so low it is almost the same level as China’s where there is a government policy of one child. We did it voluntarily. When people no longer believe more children give them more happiness they find a way to limit the number of children, regardless of church pronouncements.
It’s not guaranteed small subsidies to parents will increase fertility. If we want more children, it may take very large subsidies.
Ironically, the religious right, which opposes abortion and birth control, refuses to try it.