[mzltest]

I think the topic has too many aspects to think. When we talk about overpopulation what we should consider?
What should be the fair population in the world?
I think population density has more importance than the overall population count. People tend to live in the cities together more than the villages. We feel world is overpopulated by seeing the crowd in the cities. There is no equal distribution people in all parts of the world. I think maximum two children per couples will negatively impact the human resource available in the world. I don't know whether it is right or wrong, I heard in some countries which have such restriction have problem of not getting brides. It will lead to another problem. They give importance to male child and genocide happening in those countries.
Genocide is a human right violation, I won't support such strategies to kill a child in the womb. Every child has a right to live. We can educate people to have an equilibrium of wealth inside their family. But forcing them is a big no. It is their personal space. Education is the best thing than rules and regulations.
There may be people who don't marry, or do not have children or just one child, so this two child strategy will backfire. There will be less younger generation considering the senior generation.
For me, I think planning the population considering the density and educating people is more important than forcing the people  to have maximum two children.

Agreed.
Recently my country just loose the limit of two children per family to three and still some young people resist to give birth to a child.Controlling population often risks to an aging society as most people are living longer than before as the technology develops.By controlling the birth rate ,less younger generation is getting on the track while the current generation is aging.That would make the population structure unstable.

And,back to the title,why goverments do not control the world population.The world is not a communism world and there are no hard limits that countries have to enforce them.All the goverments are thinking in their best interest.They needs workers to work and generate profit.And so they need reasonable birth rate and you can't blame them.And so the only way for that is to control the death rate,and I don't think any country will take this approach.Having a draw to decide who will be killed?We are not living in a survival game.