I used to think the same until contemplating how many destroyed families the drug trafficking penalties of Singapore have prevented.
Considering Asia's history with drugs (European imperialists growing drugs in their colonies and then selling them to China to destroy their population), it is completely understandable and a societally acceptable trade off.
I think after a few more generations of escalating drug use harming our societal well being, we may resort to similar measures.
Urbanization and education are the two most effective ways of getting a population to have fewer children. Singapore is a highly educated and urbanized country.