It's called hypocrisy and political correctness. Since Mexico's laws about aliens, both legal and illegal are much more strict than those of the U.S., can you imagine the wailing and screaming and breast-beating by the illegals and politicians catering to them, should the U.S. laws match Mexico's?
Ship all the illegals back, whether they have "anchor babies" or not. You don't want to "break up families" of those families that have "anchor babies"? Have the illegals take them with them.