Why aren't illegal immigrant parents being held criminally accountable for the abuse of their own children as they travel thousands of miles, in the harshest of circumstances, while attempting to come to USA?

There are many who suggest USA needs immigrants for jobs that Americans "will not do" and we need immigrants to raise USA birthrates so those children can contribute to the social security ponzi scheme to keep entitlements going into the future. (i.e. infinite growth model)

The fact is, we have more than enough people in this nation which is easily understood when considering the amount of importing of resources this country requires annually. And at what point, what is the tipping point of population for USA? 500 million? 700 million? 1 billion people?