Yeah, low birth rates aren't all about money even though that's important. A lot of it is about culture, which affects women's age at first child which affects how many children a woman will ultimately have.
Even with all the incentives (subsidize childcare etc.) you'd still have to modify the harder to modify cultural reasons like people valuing independence, "casual dating"/FWB relationships for years that go nowhere is more common instead of dating with intent to marry, hustle culture/emphasis on career progress, less social pressure/shaming from parents ("why don't you have a husband/wife/kids yet?!"), freedom to "find yourself/travel" or "get sexually experienced/have a ho phase before settling" for years after college, etc.
Most people don't want to go from college to marriage and kids right away these days, and a few years of this type of casual dating/exploration after college eats up a lot of prime reproductive years. But these cultural factors are very hard to change especially with the absence of religion/strong communities these days.
Even with all the incentives (subsidize childcare etc.) you'd still have to modify the harder to modify cultural reasons like people valuing independence, "casual dating"/FWB relationships for years that go nowhere is more common instead of dating with intent to marry, hustle culture/emphasis on career progress, less social pressure/shaming from parents ("why don't you have a husband/wife/kids yet?!"), freedom to "find yourself/travel" or "get sexually experienced/have a ho phase before settling" for years after college, etc.
Most people don't want to go from college to marriage and kids right away these days, and a few years of this type of casual dating/exploration after college eats up a lot of prime reproductive years. But these cultural factors are very hard to change especially with the absence of religion/strong communities these days.