People, as a group, aren’t completely amenable to reason. If they were, they’d start from their stated beliefs of “children are innocent” and “children must be supported” and conclude that the only possible logically and morally acceptable resulting outcome would be to feed all children.
That hungry children exist, and that this isn’t a scandal which the majority of people who hold beliefs about importance of children are regularly talking about seriously trying to address, it seems that some other factors must motivate them more. Two likely candidates, to me, are convenience and status. If you can conveniently gain status by demeaning outgroups then, amazingly, you can do very little and potentially gain a lot! “I might not have an education, and I might be on minimum wage, but at least I’m not Mexican / a feminist / an atheist” etc.