A few snapshots from Cannes this week: Freida Pinto in floor-length, crystal-studded Atelier Versace, with chartreuse lace slit to the upper thigh, a slim half-peplum of gold snaking around one hip, accessorised with a metallic box clutch. Tilda Swinton in full-length, origami-folded butterscotch-toned satin, offset with artfully teased platinum hair and coral lips. Cheryl Cole, with Rapunzel curls cascading over a nude Stéphane Rolland gown, which frothed at the knee into a train of scarlet ostrich feathers. And a few more: Bill Murray in mismatched, crumpled linen jacket and casual trousers, boat shoes coming unlaced. Guy Pearce in a check shirt and jeans. And Chris O'Dowd, in open-neck Hawaiian shirt and battered suede lace-ups. A few decades ago, glamorous events held both genders to high standards of elegance. A woman in a floorlength dress would parade on the arm of a man in an impeccable tuxedo. But while sartorial standards for women have been raised ever higher - ready-to-wear is now unthinkable (only haute couture will do) and borrowed diamonds that require round-the-clock security are standard - men are swapping bow-ties and cummerbunds for untucked shirts and slackeresque facial hair. A similar disparity can be seen on almost any TV show featuring male and female presenters. The men can wear jeans and a casual shirt, but the women will be in cocktail dresses and 6in heels. There is a glamour gap between men and women in the public eye, and it is getting wider. That much is undeniable. But is this simply because modern women like dressing up more than men do? Or is there something more sinister going on? Cheryl Cole at Cannes. Photograph: David Fisher/Rex Features "Event dressing is a microcosm of how celebrity works for the genders," argues fashion historian Amber Jane Butchart. Women are held to a standard of visual perfection that simply does not apply to men. Red-carpet dressing for women has become about creating a look that is almost superhuman, and this reflects a broader truth about modern celebrity: that women must achieve perfection to avoid criticism, while men have an easier ride. And yet the sexual politics of red-carpet dressing are not black and white. The shift toward a focus of female glamour also reflects the monetisation of the red carpet, which has proved more lucrative for Hollywood women than for men. Robert Johnston, associate editor of GQ, noticed the glamour gap at the Met Ball earlier this month. I thought it was very striking that the women were wearing almost museum-exhibit level fashion, whereas the men were in regular black tie. For female celebrities, fashion has become exaggerated because the designers are using them for marketing purposes, and they are using the designers for publicity purposes. It is an unholy alliance, but it works. For many female actors, makeup and haircare campaigns are where the serious money is to be made. It is no secret that those contracts are landed by looking incredible on the red carpet. Bronwyn Cosgrave, the author of a book on Oscar fashion and curator of an upcoming exhibition about style and James Bond, says: "Getting the right image of yourself at Cannes is money in the bank. These are not just fashion moments for these women - they are deal-clinching moments. This does not only apply, she points out, to the blockbuster hair-mousse-advert end of the market. Tilda Swinton is someone who has managed to make an artful, individual career combining interesting films and high-end fashion. Seen from a financial perspective, it is women who are in the position of power. In many cases, a fashion house will dress the husband or boyfriend of the "face" of their label simply to avoid him spoiling the picture. When you have invested heavily in a glamorous face, you must protect that investment. Chris O'Dowd at Cannes. "None of this is a new phenomenon," argues Cosgrave. Cannes has been about starlets since the days of Brigitte Bardot on the beach. And Hollywood has always opened magazines to cast movies. Lauren Bacall was spotted when the studio mogul's wife saw her photo in Harper's Bazaar. Because the red carpet has not taken off as a money-spinner for men in the way it has for women, men's clothes tend to be a more realistic reflection of the increasing casualisation of dress. According to Gareth Scourfield, fashion editor of Esquire, they also reflect the Americanisation of our world. Americans don't have Savile Row; they have bomber jackets. And as a result American men don't really understand tailoring like the British and Italians do. Age-old differences between the sexes may also come into play. "I've seen men at the Baftas who so clearly should have had their trousers hemmed, but they probably didn't try the suit on until five minutes before they had to leave," notes Scourfield. That just wouldn't happen to a woman. Men who have grown up in a dress-down era are also often confused and intimidated by the rule-bound world of men's formalwear. "It can be intimidating," agrees Johnston. How many buttons to fasten on your jacket? How many inches of shirt sleeve should show under your jacket? Men these days just don't know this stuff. That might be true, but in the final reckoning, there is no doubt who gets the easier ride. As Cosgrave puts it: "Johnny Depp looks dishevelled on the red carpet, and all the coverage is about how cool and maverick he is. But if an actress has a hair out of place, or a tiny wrinkle on her frock - she's having a life crisis. That is how society judges those photos. There is no doubt that it is incredibly unfair.