It is nothing to do with older women, it is all about middle age women. Older women, 70 - 75 plus are generally not at work, and while they may be caring for grandchildren, most will have older grandchildren and they are very unlikely to be caring for their parents, although they may well be caring for a spouse or sibling. As for older people in the media, we can be seen regularly in adverts for stair lifts, incontinence aids and care homes.
In media and political eyes once you are 70 you aren't a person anymore you are just a burden - on your children, the NHS, on the benefits system. It is conveniently forgotten that most of us have been working and contributing to the common weal for 40 years or more and that most of the people who see us as a burden depended on our taxation to pay for their education, and health care etc as children