When I was in school and read about the population problem of the country, I thought that every problem in the country is because of this huge population. I thought that if population can be controlled, most of the problems can be solved. I had the same question, why Government does nothing to control it.
Now, after growing up, I have seen and experienced that this huge population is not generally considered as a problem by many. Even, Government talks about the problems of Poverty, Corruption, Inflation, Security etc. but ironically, Population is never an agenda.
Actually, people are considered as resources and kind of asset. Man-power, they call it. Though, with changing times, families in India are not getting as big as they used to be in past. Now, people have generally two or three children at max. in contrary to the minimum of 4-5 children in past. One mentality, especially in poor families was that, if you have more children, you will have more sources of income. i.e. they will grow up and earn money for the family. This is also changing now, probably.
As far as Government is concerned, though they do not talk about population as a huge problem, there are Government schemes in place which spread the message of the benefits of less children (Hum do hamare do - an old campaign that promotes having two kids at max.).
Govt. also has several schemes in which benefits are given to families having one or two children OR cancellation of benefits for the families having more than three children.
Things are changing at the level of individual with time and I feel, it will get better with time.