Take the level of formality in a culture to be how much variance in behavior is allowed for members of the major groups that we carve society up into -- men and women, young and adolescent and adult, patron and client, initiated and neophyte, ruler and ruled, etc. More formality simply means that members of one of these groups are more locked into their expected role, regardless of what that expected (or average) behavior is. Less formality means that more variation is allowed. Mary Douglas referred to this social variable as "grid," Victor Turner "anti-structure," etc. I'll use the simpler term "informality."
While watching the DVD for Live Aid, I was struck by how tame the English concert has been so far, compared to the American concert, both from the performers and the audience. I'd always heard from interviews that American audiences work themselves into more of a fever pitch compared to English ones, and that this led the band members to give a more energetic performance to American crowds.
English society has been more formal than American, so the chasm in enthusiasm is as we would expect. The more that formality matters, the more self-conscious you must be in order to make sure that you're not stepping out of your proper role. With formality constraints relaxed, you can slough off your self-consciousness and enter a more trance-like state, similar to spiritual possession, and abandon yourself to the carnivalesque party atmosphere.
The even more formal society of France (at least around the cultural capital of Paris), which prides itself on bourgeois propriety (and courtier life before that), has never produced a major popular music sensation -- that is, beloved by many outside of France -- let alone in rock music. (While many know who Edith Piaf is, few listen to her over and over.) Not that rock music wasn't popular in France. They just couldn't let their hair down enough to make it themselves. This shortcoming is not just in popular music, as though they specialized instead in higher art forms, since the French were also-rans in European Classical music, behind the relatively less stuffy German-speaking and Italian countries. Germany did fairly well in rock music, and though Italy did not, they did play a leading role in European dance-pop music.
Aside from the bird's-eye-view of how popular a certain form was in the entire society, or how good that society as a whole was at making it, let's look at groups that tend to be more on the margins of cultural production and see if the pattern holds even there. For instance, women are outnumbered by men in any area of culture that is at all exciting and meaningful. Nevertheless, we predict that more informal cultures will allow women greater lee-way in their behavior. Cross-culturally, greater informality is one background condition for religious activities where female spiritual possession plays a key role.
Starting with the line-up at Live Aid, of the 20 groups performing at Wembley, only 1 featured a female (Sade), whereas among the 33 groups at Philadelphia, 6 did (Joan Baez, The Pretenders, Madonna, Ashford & Simpson, Thompson Twins, and Patti LaBelle).
In the Rock and Roll Hall of Fame, there are mostly male musicians and from both America and Britain (and a few other places too). But of the females inducted, my rough count is 22 American individuals or groups with a prominent female, only 1 British individual (Christine McVie, who was in the American band Fleetwood Mac), plus 1 Canadian individual (Joni Mitchell) and 1 Swedish group (ABBA). Most of the Americans are more R&B / girl-group performers, but there are still a good number of more rock-oriented artists.
Finally, consider Wikipedia's list of female rock singers. I'm filtering out those who never made it big in either the mainstream or a large sub-culture, who were one-hit wonders, and who were famous for being famous. This is a subjective reckoning of who made a fairly large direct contribution to the genre. I've split them into what I consider lesser and greater importance, and by American or British location. This gives:
Sure enough, the big female rock stars are all American, reflecting the less rigid sex roles of our society. There are some British females in the second tier of rock eminence, but even here we see that they're not so much English as Celtic. Kate Bush's mother is an Irish folk dancer, Annie Lennox is Scottish, and Bonnie Tyler is Welsh. Here I'm not so sure, but my impression is that the Celtic areas are more informal and casual than England. At the regional level in America, we should see more accomplished females as we move away from the high-point of formality in the northeast, going west and south, which looks roughly correct. At any rate, the American vs. British difference is clear.
Some level of formality is good just so people don't get totally confused about how to behave in this or that situation. But it's remarkable how little we apparently need in order to hold up most social institutions. More importantly, a low level of formality is the most important part of moving a culture forward -- the less blind variation there is, the harder it is for the survival-of-the-fittest dynamic to find better culture and weed out the lesser. The wide range of variation that comes from more informality isn't good in itself (since it produces a lot of garbage, too), but only to the extent that it's the first step along the path of upward cultural evolution rather than stagnation.
This is especially marked in the areas of culture where a loss of self-consciousness is one key part of the experience, such as the arts vs. the sciences, fiction vs. non-fiction within literature, ecstatic vs. rational sub-cultures in religion, and so on. Fortunately for the more fun-loving societies, we can easily reproduce the fruits of the rationalistic and self-conscious labor of more formal societies -- build airplanes, set interest rates, etc. It seems much tougher for those more formal societies to take the products of our footloose culture and get the same enjoyment out of it. The same applies even within a society: a more don't-fence-me-in sub-culture thrives most when there is a more tightly rule-governed sub-culture whose benefits can be spread easily to the former.