Earlier quoted context omitted.
I can't comment on US, but Germany and some other EU countries have fertility rate below 1.5. Without immigration the system will collapse as pensioners will outnumber working population. EDIT: this is an observation, I am not advocating 'substitution'
Yes, lets bring in loads of uneducated, poor immigrants instead of addressing the issues causing fertility rates below the replacement level. Why let our children have families when we can import them for cheaper?
Myself and many of my friends who have decided to have zero children or only one child rather late in life, cite the burden of having to take care of children, when one is already tired after work, one would like to pursue leisure activities that do not involve children present, etc. Even in countries where the state provides abundant infrastructure to minimize the financial expense of childrearing, birthrates are still low because of the time and effort expense that remains. So, how do you address that issue? Telling people to just suck it up and accept childbearing as their duty isn’t going to work.
Immigrants are often coming from countries where religious and cultural pressures in favor of childbearing are maintaining the birthrate higher than in the West, but even in those regions birthrates are gradually falling as their countries become more developed.