You kind of are full of shit.  Every public high school here has a theater department, and most universities do too, along with pretty excellent performing arts universities too, like Julliard.  Oh, and lots and lots of summer theater camps.  So kids in The States, if they are so inclined, have a ton of options too.

Laurence Olivier!  Seriously, watch him in movies and he's so ridiculous, like in 'The Prince and the Showgirl'.  I'm sure he was one hell of a stage actor but I don't think he comes across as natural at all onscreen.

British actors are, maybe, better trained for theater, but I don't think this necessarily makes them better actors for movies and tv.  In my opinion, a lot of them are really fuckin' hammy and/or stiff on camera.