> any deviation from that is no longer a transcription

That's a wild exaggeration. Professional transcripts often have small (and not so small) mistakes, caused by typos, mishearing or lack of familiarity with the subject matter. Depending on the case, these are then manually proofread, but even after proofreading, some mistakes often remain, and occasionally even introduced.

maybe, but typos are not even the same thing as an LLM thinking of better next choice in words than actually just transcribing what was heard.