Let us speculate only on 2 working moms.
Abby works full time but needs assistance with child care for her 2 childern aged 6 months and 3 years.
Susan works part time in the evening so her children (same ages) are always with a parent. They have enough money for bills but need pa for food.
If Abby cut her hours she wouldn't be able to pay their bills, and if Susan worked more hours they would need daycare as well. Which mom is more "worthy" of your tax money?