I have been pondering this question lately as I have noticed that it is mostly older men that open doors for women anymore. Younger men tend to go in first and let the door hit you as you walk through. Though I am a woman, I tend to hold the door if I get to it first and will hold it for men or women....I open building doors for men, children, old women, and young women who don't carry themselves with an attitude. I used to open car doors for women, but I don't anymore because I got tired of feeling stupid every time I went to the other side of the car only to stand there uselessly as the woman, already in the car, closed the door herself. I suspect remote door entry might play a role in that, but it might also be simple female impatience.
I can understand why men no longer want to open doors or help women. I do feel sad, however, that it has come to a situation where society is at this level. In fact, in my forthcoming book on the war against men, I address how our society is breaking down because men no longer want to, or are even afraid to interact with women and girls.
It's probably a character flaw, but I do tend to get a minor kick out of the affronted look on an entitled modern princess's face as she arrogantly marches toward the door, expecting me to dutifully hold it open for her, only to find it closing on her face. It actually took some time to unlearn the habit, as I had been raised to always open doors, but as with the car door situation, I got tired of encountering the negative reactions. I suppose the instinct to help women is still there, but it is now easily quelled by experience and reason. The change that Dr. Helen is noting is reactive behavior; don't blame the young men, blame the women who, instead of simply saying "thank you" or even just smiling in response to having a door opened for them, sniff haughtily or sneer in contempt instead.
So, my answer to Dr. Helen is that whereas it was once the social norm for men to open doors for women, that is no longer the case and it will not be the case again until men and women finally reject equalitarianism. Unfortunately, we will probably have to go through a cleansing period of behavioral barbarism before society can be expected to return to some of its civilized practices.
Personally, I think bringing back dueling wouldn't be the worst idea.