I agree with you and the person you're responding to, but I also understand where the anti-child-tax people are coming from. I think they come from a good place, which is "I shouldn't pay for optional activities of others" and probably some amount of "why pay for THOSE people's kids who are just a drain on society's resources (and mine personally!)".
But if "those people" (trailer park folk, the uneducated, or whoever else somebody dislikes) are going to have kids, wouldn't we all prefer that they at least get a minimum education, basic nutrition etc. so that we don't push them into being an un-educated, malnourished mob that resents the rest of society?
Public education, welfare, etc. might be broken, but that's a whole other argument.