I think it's pretty safe to say that paying cash for every child falls squarely in the category of "rewarding behaviour you wish to encourage", let alone subsidised housing, tax breaks and paid maternity leave. There are obviously degrees of encouragement or discouragement, but that's beside the point. Which, in case it wasn't clear, was that these measures only have a hope of working with low-income households as the advantage of fixed-size benefits (cash child benefits, paid maternity leave) diminishes proportionately, and the rest (tax breaks, housing) are inversely dependent on income.