An anonymous review in IMDb of Butch Cassidy and the Sundance Kid, which says what I've long thought (or maybe I just think I long thought this, because I never put into words) about this movie:
Seeing this film again on DVD -- more than 30 years after the first time I saw it -- I'm struck by two things. First, it holds up well for a movie so redolent of a particular time (the 1960s, of course, not the 1890s). Second, whether the filmmakers fully intended it this way or not, it's really a very good film about a topic Westerns don't tackle often: arrested adolescence.
Most great Westerns -- ``My Darling Clementine,'' ``Rio Bravo,'' ``The Wild Bunch,'' ``Unforgiven'' -- are about adults. ``Butch Cassidy and the Sundance Kid'' is about two guys who, physically, are pushing 40, but whose mental age is stuck somewhere around 16. They may be charming, but their whole lives revolve around their narcissistic pal-ship. For them, being outlaws doesn't seem to be about expressing anti-social impulses or even getting money they haven't earned, but merely about hanging out with each other. Their talk with each other is mainly brittle ritualized patter and stock jokes, mixed with Butch's pipe dreams. They can't talk about anything serious even at the end, when they must realize -- at some level -- that they're about to die. Screenwriter William Goldman emphasizes the oddly callow, adolescent tone of their relationship by repeatedly having them express surprise when they stumble over some bit of biography -- their real names, or the fact that Sundance is from New Jersey -- that you'd think real friends would have known about decades ago.
The movie's whole point is that Butch and Sundance can't develop any type of dramatic arc. Harshly changing times demand they change with the times or die -- and they can't change and ultimately choose, by default, to die. They do get a huge lucky break when they get away from the Superposse _ but all they can think to do with it is change not what they're doing, but merely where they're doing it. They can't even change enough to keep Etta Place with them, even though both Butch and Sundance really do love her, in their way. (Etta, in contrast to Butch and Sundance, is harshly realistic about her life and her limits -- she knows she isn't strong enough to die with them or to see them die.) Butch and Sundance, as far as we can see, don't care about much outside themselves and Etta.
This is why the movie's ending -- that famous freeze frame -- is so perfect. Butch and Sundance are secure, together, in their niche in history. They don't have to worry about changing times or the baffling world outside themselves any longer. They've won out over time and change -- the only way anybody ever can.