Here, most people would also say no - they'd want the "bonus" for children to be equal for low- and high-income families, but they do not want the "penalty" for lacking children to be the high for same and low income.

Note typo.

Great post! I actually started trying to argue against your analysis here in the child tax example, based on my own intuition. Then I realized I was being a sophist. I had good reasons for both preferences, but the reason for the progressive penalty wasn't applied to the flat bonus, nor vice versa.

I might have to be careful about how this 'politics' thing affects my thinking.