the difference is, that a model is literally just numbers.
proprietary software is data and code, and while it's true that code is data, the difference is that some data is intended to be for control flow, while in a model it is all the same stuff.
You can point to any single part of an LLM's model and say "this here is a weight" but if you point to any single part of a binary file you will have no idea what you're looking at.
And yes, you could decompile the binary, but that still doesn't give you the entire picture, and all proprietary software does the shady shit on servers these days anyway so you're not even going to find anything interesting.