It's true - in France they spend a TON more money than in the US on "treatments," from skin care to anti-cellulite creams to supplements targeted to just about anything. Trouble is, French women are (sadly) still more likely to stay slim via aging methods, like drinking heaps of coffee and smoking and that certainly takes its toll on their skin and teeth. And I don't know any French women who wear sunscreen daily - of my younger French acquaintances, those who wear it at all only do so when going to a beach or spending a full summer day outside the park or garden.
So, I actually think that French women - especially older ones - often have much worse skin and teeth than their American sisters, with more bags under their eyes and more lines (from smoking) around their mouths. Also, orthodonsitry and dentistry weren't popular in France until recently (and, I can't tell you how many 30-something friends I have who haven't been to the dentist since they were kids), and older french women's teeth definitely show these decades of neglect.
The average French woman IS darker than the average American, so if you took both groups of older women and never applied sunscreen, the French ones are less likely to have accumulated years of sunburns that Americans might have had... given that in the 1960s and 1970s, sunscreen wasn't popular on either side of the ocean. So, that helps the French aging process, I suppose.
And yes, maybe plastic surgery isn't as common there as it is in the US (in part, because France is still far less affluent than America) BUT, I do have several French friends who've had work done (one, in her 40s, to reduce under-eye bags; another, in her 60s, with an eye lift) and I find it funny that they article uses Catherine Deneuve as an example since her face has been pulled and prodded within an inch of its life.
Older French women seem to win out, though, when it comes to their style. I've seen heaps who dress in a way that I find extremely unappealing, BUT they do seem good at avoiding that 60 years-old-dressed-like-a-teen look that I think makes some older American women look foolish and, well, older than they really are. They pay a LOT of attention to getting hair cuts and keeping them maintained (even though I generally find the hair colouring to be much worse than in the US). They tend to not do the stiff hair spray/ "helmet hair" that some American women favour.
And they do tend to keep their figures slim - although they don't generally do much exercise so they don't have much definition/ muscle tone.
I think it's pretty sad that Americans love to look at women from other countries and say, "ooooh, they're all so much more attractive than we are." Because I don't believe for a second that it's true. And in France, they love to look at women from other countries and say, "ooooh, they're all so much LESS attractive than we are." And I absolutely don't believe That's true.
So, to sum up this long note, I think there are many things that French women do well when it comes to their looks but many things that they do badly. The biggest difference is just that they even the ugliest and least stylish (*cough* my partner's mom *cough*) think that, as French women, they are the most elegant and sexy people in the world whereas American women generally don't project the same level of innate confidence. C'est tout!
(as a Canadian, I've been able to observe both cultures as an outsider and I just wish that Americans would accept and embrace their own attractiveness!)