Addressing the implication of breeding for money, I actually prefer the solutions explored in Larry Nivin's main fictional universe.

Importantly, in that universe, different regions of human colonization had different limits for births; including un-affiliated areas (space between planets) having unregulated birthrates.

For the context of Earth/Terra:

I forget if it was one or two children, but for sure, for two parents 'the first child is free'. Let's simplify that and say that for each contributing parent (to society) the first child is free.

After that additional children slots can either be obtained through exponentially larger tax payments, performing a significant contribution to society (E.G. Nobel Prize winners might be granted unlimited reproduction rights), or winning a lottery.

Obviously in the case of massive global war, famine, or disease (age death waves included), additional children might be built in to the quota to keep the population at desired levels.