Widow, you must live in an interesting place where all human beings primp and preen. It's certainly not anywhere I've lived in the UK or the US for that matter. If one sits in a public place like a shopping mall or district, a leisure centre, a museum, etc., where alot of people are coming and going, it's very easy to see a gendered difference in the level of attention paid to appearance. Surely you aren't suggesting that men and women generally pay equal attention, money and time to their appearance, seriously? As many men's beauty and hair salons as those for women on the high street? As many male cosmetics for sale as women's?
As for hair, I believe any person should be able to wear their hair as they wish, short, long, natural colour, dyed, thick, thin, bald, wig, whatever they choose.
I think both men and women are more likely to be critical of women for having the wrong kind of hair, whatever they choose (e.g. letting it go grey, roots growing out, too dowdy, not "right" for the age, etc.) That, in my view, is just part of the common belief within our culture that the most important value of women is in her appearance (or at least if she achieves other things, she shouldn't "let herself go," - witness the crap Hilary Clinton, Margaret Beckett, Angela Merkel and other women politicians and leaders get for the way they look - something that rarely happens and never happens with such regularity for men in similar roles.
Myself? Fancied reinventing myself as blonde a few years ago, having been every other colour. Silver will be next when I'm bored with this barnet. 