The cost in time energy and money to have a kid is insane.

Then add on that pregnancy is a high risk activity in a country where health care costs can be prohibitive. Maternity centers are closing, strange fetal life laws make doctors at the ones still open hesitant to act and you have increasing maternal mortality rates.

A society that has become increasingly mobile and less family connected has removed a lot of the support structure that is healthy for new parents.

A general feeling of "the end is nigh" caused by a 24 hour news cycle where bad news sells, fear is a political strategy, and people are burdened by the problems of 7 billion other people leads to helplessness and despair and not the hope necessary to want to bring a life into the world.

Those are just 4 of probably dozens of reasons people are delaying or simply giving up on having children. Trying to force births or giving a tiny tax credit are bandaids on a much wider problem and until politicians are willing to really look at ALL of the issues not just their pet peeves I don't see much likelihood of improvement.