I agree with your last sentence. The important thing should be how much good does the charity really do to those children. Are they really making their lives better, or is it merely some nonsense to "show that we care"?

Because there are many charities (at least in my country) focusing on providing children things they don't really need; such as donating boring used books to children in orphanages. Obviously, "giving to children in orphanages" is a touching signal of caring, and most people don't realize that those children already have more books than they can read (and they usually don't wish to read the kind of books other people are throwing away, because honestly no one does). In this case, the real help to children in orphanages would be trying to change the legislation to make their adoption easier (again, this is an issue in my country, in your part of the world the situation may be different), helping them avoid abuse, or providing them human contact and meaningful activities. But most people don't care about the details, not even enough to learn those details.