An acting teacher of mine put it this way. “It comes down to schooling, when young women and men study acting in Britain it’s expected they are going to work. They cut their teeth often in the theater they are expected to discipline themselves and they don’t get by on just having a pretty face. In Britain they take a lot of pride in the arts and they have more public money available as having great theater where up and comers can get a start is a thing of pride. Also the shows in Britain have a broader range of characters, actors have a better chance to develop skills that turn them into working actors, as they are EXPECTED to become.
Here, we have method acting, identity politics, schools get teachers who can’t get a job somewhere else so they become teachers. We don’t really have public money for the arts so young actors don’t have the same opportunities to cut their teeth in the theater. Like someone else said we rely on stereotyping in casting so actors are expected to brand themselves as a certain type rather than learning to disappear into a role.
And that thing again about work, actors here aren’t taught to value the skills they learn as much as the image they project. They go to school with very little expectation that they will get a job. To get a job you work on your image, getting plastic surgery, networking, quite a few women at least get married to a director or producer, that’s something that will help your chances.
Also, Being a good actor requires a lot of empathy and vulnerability, Someone who can do this and put up with the being phony stuff and not do a Francis Farmer or River Phoenix is rare. It’s not that British actors don’t do these things, but British actors are more likely to have the skill to back up the position they are in once they get there and they are taught in a way that helps them prepare. Basically we don’t have a system that values art, outside the god almighty dollar.