> But they really can’t due to economic circumstances.
I don't think this can be the entire situation. Anecdotally, both my wife and I have grandparents who lived for extended periods of time with three kids in mini camper trailers because they couldn't get into any other housing. They really wanted children, and it was a high enough value for them that they sacrificed a lot to have them.
Additionally, economic prosperity and higher living standards are typically correlated with lower birth rates. People who technically can most afford children, are less likely to have them. This is the opposite of what I would expect if finances are what prevent people from having children.
Having children now, I cannot fathom living in a camper trailer with them, and I am not saying that people should be doing that. My point is that different people (across different economic situations and different time-periods) have varying priority levels around having children. And that is ultimately what determines how many children are born.