Years ago, when I was much younger, I would've easily ranked "Butch Cassidy and the Sundance Kid" as my favorite western; I think it's a lot of peoples' favorite. However, the older I get, the less I feel able to defend it. I barely think of it as a western these days, and that's part of the appeal; it's a western that doesn't feel like a western, even back then that was the appeal. The movie feels less like a western and more like, "Easy Rider". (Or more like, how "Easy Rider" should've sounded like.) It's one of the most beloved screenplays of all-time, from one of the most beloved screenwriters of all-time, and it is a great script, and has one of the greatest lines of dialogue of all-time, at one of the most dramatic and iconic of moments of all of cinema. On the page, with the dialogue, and story, it works, but, still, there's a scenes where, the Oscar-winning song, "Raindrops Keep Falling On My Head" plays, in a western, and on bright sunny daylight, not a cloud in the sky. I mean, you can argue it's supposed to be anachronistic, well, having a modern pop song at all in this western makes it anachronistic, but that song..., in that scene, with Paul Newman and Katharine Ross trying to ride a bicycle?
The actual story of Butch Cassidy (Paul Newman) and The Sundance Kid (Robert Redford) is basically there, although I'd have trouble calling it accurate. In fact, to some degree, it's so inaccurate that, I almost get the sense that this film would've worked better as a musical in the vein of "Hamilton" or "Bloody Bloody Andrew Jackson".
(Pauses. Idea lights up. Writes down note: "Look up musical rights to adapt "Butch Cassidy and the Sundance Kid"...)
Ross's character, Etta Place was actually a prostitute not a schoolteacher for instance, and while they're claim to fame as legendary bank robbers of the Wild West is firmly in place, and yes, they're big claim is that they became successful heroic robbers on two continents, first in America, and then they went down to South America and did it again after the Hole-in-the-Wall gang disbursed. The movie, isn't so much about their success as it is, a comedy about it. Any attempt to watch the movie to get a sense of Butch & Sundance the people is a fool's journey; it's practically as dumb an idea as watching Tarantino's "Inglourious Basterds" in an effort to find out more about the real Hitler.
What we do find are two tragic, funny, modern-day heroic anti-heroes in the Old West. They act like their Buster Keaton, two funny things in a strange world, but they're more like Charlie Chaplin, where they're the funny thing in the real world, and the real world is coming to get them. These aren't John Wayne archetypes, they seem more like, two guys who probably idealized the devil-may-care tough guy attitude of Steve McQueen but grew up with the fragility and empathy of James Dean. And despite all the logic problems with that modern-day wit and sensibility, clashing with a time period western, it works, not in spite of it, but because of it.
That's probably the real secret as to it's greatness, why it continues to survive and refuses to go away, not because of it's failings as a western, but cause it succeeds at what this film actually is. It's one of the greatest and quintessential buddy comedies of all-time.