So, it's a bit like complaining that tinted windows work better to reduce sunlight on TV than in real life. Or conversely that people whispering in the movies are way too loud, since you shouldn't be able to hear it all the way at the back of the crowded theater.
Also, sound effects are very stereotyped in the media. They are nearly a symbolic code, not realism. Hollywood shoes don't sound like shoes. Hollywood beverages don't sound like beverages. Hollywood clothes don't sound like clothes. Hollywood sex doesn't sound like sex.
Also, these conventions were being established for worse sound systems in old theaters, TV, etc. You cannot reproduce actual gunshot sound experiences in a movie. They are already "silenced" just to fit into the playback environment. So what else can you do to portray a suppressed weapon after that? Of course, you'll need to reduce it even further to make it unambiguously different.
Edit to add: I recall how Dirty Harry's magnum got what seemed like a new sound effect at the time. Not only is the sound smeared out in time, it has a ragged edge like a clipped signal. It is reminiscent of the recorded sounds of space launches that were culturally widespread by then from the Apollo program.
This bit has me perplexed. If you had a single message that you wanted to send multiple times in different forms, wouldn't compressing the message exponentially limit possible variation whereas expanding it would exponentially increase it? If you had to send the same message more than a couple of times I'd expect to see accidental duplicates pretty quickly if everyone had been instructed to reduce the message size.
I guess the idea is that if the message has been reduced in two different ways then you have to have removed some information about the original, whereas that's not a guarantee with two different expansions. But what I don't understand is that even if you have a pair of messages, decrypt one, and manage to reconstruct the original message, isn't the other still encrypted expansion still different to the original message? How does that help you decrypt the second one if you don't know which parts of the encrypted message represent the differences?