Giving people cash to have babies works, just not very efficiently. It’s expensive. In the U.S., we’d get one baby per $200,000 to $400,000. Lifetime taxes paid by the average person is $150,000 to $400,000. So fiscally, the government may break even. Childless people are dependents on society so should pay higher taxes. Their future retirement depends on the labor of younger people, and younger people depend on the labor and money of parents.