The left has bastardized the argument by bringing the notion of equality into it. It has nothing to do with equality, but more to do with what is being distributed. Suppose, for example, that you have a large surfeit of apples that you wish to divide amongst your ten friends. The apples are divided, and each friend gets an equal moiety. One of the friends, however, is not satisfied. He doesn’t care for apples, and insists that in the name of equality you give him pears. But in effect, he has not been treated inequitably, because he has had the same thing and in the same proportion as the other nine.
Your argument is excellent by try getting them to listen to it. They will only say, “But we were born with special digestive systems which can only digest pears and not apples.”