This is just stupid.
'Lady' carries with it overtones recalling the age of chivalry: the exalted stature of the person so referred to, her existence above the common sphere. This makes the term seem polite at first, but we must also remember that these implications are perilous: they suggest that a 'lady' is helpless, and cannot do things for herself. In this respect the use of a word like 'lady' is parallel to the act of opening doors for women -- or ladies. At first blush it is flattering: the object of the flattery feels honored, cherished, and so forth; but by the same token, she is also considered helpless and not in control of her own destiny.
--Robin Lakoff, Language and Woman's Place 25 (1975)