Screenwriters, attempting to grab the attention of a reader, would break the fourth wall with self-referential comments. Shane Black scripts are known for such chatty asides, to the ire of many. There's a fine line between breaking the fourth wall, which I'm against, and a really good, effective, concise description. That's dangerously close to a chatty aside, but it's also a great character description. It gets the point across using the least number of syllables.
People tend to think of screenplays the way they think of novels.
In truth writing a script is much more like writing poetry. The form and structure are paramount, and the goal is to convey as much information as possible in as compact a form as possible. Not only does every word count, every syllable counts. Song lyrics are one form of poetry. I prefer to think of screenwriting as song writing.