I think even calling it "society incentivizing people to have children" is a bit of a stretch, since in most cases the tax advantages are unlikely to result in a net financial advantage given the financial costs of raising children. In most cases the thought isn't "I'm ambivalent about having children but I will do it for the financial benefits" and rather "I'd like to have children, but it's very expensive, and the tax advantages slightly lessen the expensive."

This has been my experience as well, childcare alone is a pretty big part of my budget. I am definitely not better off financially by having a toddler :D

I still think of it as incentivizing in the same way the EV rebate helped encourage me to buy my first EV, even if the cost of the car still was more than I would have been willing to pay for an ICE car. It made a difficult thing (slightly) less difficult.

Incentivizing doesn't have to mean that the incentive alone makes it worth to have children. It just means that it makes it a better deal than it would have been without the incentives.

Single also differs from being in a childless couple e.g. in your early 20s.

To get on the ladder today, 5 years sharing rent is priceless. Then once you do, you get child benefits. Many people are single late in life too. So I don't think it's something you can equate.