I feel like there really hasn't been sincere data-backed methods with proper resources behind them, for example governments giving out minor cash benefits to parents of a few thousand dollars when that's a drop in the bucket compared to the total cost of raising a kid and is not going to convince anyone who wasn't already going to have kids.

Also, that's a wild solution. You'd have to do away with monogamy which would cause some pretty insane societal shifts. However, as a straight guy I can see the appeal lol.

The issue with low TFR seems to be difficulty of forming relationships, not failure to have children once relationships are formed.

I'm imagining it becoming a social norm for single women to have (at least) a single child. Perhaps they'd team up to make raising them easier, forming loose family-like units. Romantic attachments would be optional.

One consequence of such a situation would be an incentive toward private positive eugenics. Women would prefer semen from top quality donors.

At least in the UK the cost of childcare is a major factor putting people off.

People simply can't afford to send a kid to pre-school childcare because it's 2 or 3 thousand GBP per month. So you have to stay at home to look after them, but then you can't afford the rent/mortgage and/or food because you're not working. Woe betide you if you earn over 1 penny over 100K GBP because then you get zero help with costs.

They need to provide more government funded (i.e. universally free non-means-tested) pre-schooling like they do for 5-18 year olds.

I love this as a science fiction thought experiment but altering the male/ female ratio will never happen.

If someone tried to implement it- aside from the obvious problem of authoritarianism- the resulting male minority would live life in romantic "easy mode" so people who want the best for their kids would want male children and rebel against a system more likely to give them female children who would find romantic prospects difficult.

I suppose if someone invented a way to alter sexuality to allow straight women to opt into becoming gay the romance problem could be mitigated, but I'm guessing that this is impossible given the human brain is only so neuroplastic in adult years.

As Jan and Dean put it in Surf City: "two girls for every boy".

Or more. The prevalence of males seems to be an unfortunate consequence of evolution. There's an evolutionary equilibrium of nearly an equal chance of a male or female offspring, even though the ability of the species to reproduce would be higher with mostly female offspring.

I wouldn’t be surprised if historically there were more women than men due to accidents involving mammoths or clubs meeting skulls.

Without a major and unrealistic cultural change, 2 girls to share one boy (polygamy) is not going to happen.

No no, not like that. Well, maybe, but no. Most men are useless from a reproductive standpoint because they're not the bottleneck. Women are the bottleneck. More women means no more bottleneck, means more children per person.

Also sexual selection is a thing and I think we were really never meant to have this many men. Men seem good for being really successful or otherwise dying, not much in the middle.

But also, all this talk is purely from a reproductive standpoint. Human societies also need to consider fairness and rights.

All you said is correct, but all you said points towards polygamy.

If TFR stays well below 2, there's going to be major change sooner or later. The question becomes which change. Maybe the Amish will take over the world? Or maybe some solution we find really weird will be adopted by some other minority and they'll dominate.