Fair enough I suppose. I guess I just find it rather ludicrous that people would try to claim that "there is no script" when it's so obviously false. What is an adventure if not a script?
This is the problem you keep running into. It is not self-evidently false. In fact, I consider that it takes a very high degree of abstract reasoning to picture an adventure as a script. An adventure is not a script. An adventure is an adventure. An adventure is somewhat analogous to a script (maybe), but it is not actually a script. You can't take an RPG adventure, go to a theater, hand it out, and expect actors to make heads or tails of it. It's not a script. It serves a somewhat similar but also very dissimilar role to a script, and it has features that a script generally lacks (like for example a map) and lacks features that a script generally has (like well, a script).
Whether you write the adventure yourself or buy a module, it's a script for what's most likely going to be played that evening.
You are using script very loosely here. I think more clarity is had if you use the terms to mean what they mean, instead of reaching around for terms from other arts. An adventure might be a manuscript or it might be a book. It is not the written text of a RPG play session, which is the normal sense the word 'script' has when we use it to speak of plays, movies, television programs, etc. The actual script - the transcript - of an RPG session cannot be producted before hand. An adventure is something both similar and different, and actually I prefer the common jargon 'module' to refer to a detailed description of a portion the game space that can be explored and which is joined by some common idea or plot.
That the script is not adhered to often, and the script is often very vague, doesn't suddenly mean that there is no script.
There is no script. There is something like a script in as much as you can take a script and add players and get a play and you take a module and add players and get play, but its not an actual 'script' in any normal usage of the word. Now interestingly, an adventure might contain an actual script that the DM (or even the players!) are supposed to recite, but especially in the case of player recited scripts this is generally seen as poor practice (although some famous modules have experimented with it and some players like it). On the other hand, for a real script, to not have dialogue for the players to recite would be seen as avant garde at best and ridiculous at worst.