That's a bit of a weird point to make, though. That income tax is already going toward paying for government programs. If you divert some of that to pay for early child care, some other programs will be left under- or unfunded.
Left people feel emotionally obligated to spread their “correct” opinions that “help people” as far as possible. Nationally > state.
The main difference is that the federal government can 'print money' to fund spending (the most recent tax cuts were essentially funded that way) and hope that long term economic growth from the policy change negates the increased deficit.
The second reason is that the Federal government takes more of the tax pie than states do. According to this link[2], the federal government gets 65%, states take 20%, and cities/municipalities 15%. And keep in mind that a good chunk of the federal money goes back to the states via federal programs. So if you are going to target your policy initiatives, might as well aim for the biggest slice of the pie.
[1] https://www.chs-ca.org/child-care-payment-program [2] https://www.taxpolicycenter.org/briefing-book/what-breakdown...
For example, Utah's tax revenue was $9.9 billion in 2018-2019. Federal was $3.6 trillion. But Utah only has 1% of the US population. So if the rest of the states taxed at the rate Utah does, that would be $990 billion, which is about 1/4 of the Federal take. It's way more than 5%. And Utah is not a high-tax state.