You've always been allowed to transcribe (ie, write) out a conversation. Recording is a different thing. A person can always claim, easily and believably, that the transcription is made up. It's just text.
From a legal perspective you can't record something in many us states. Using the microphone, keeping the bits in memory while you turn it into text, probably doesn't meet any reasonable definition of "record".
Maybe this will be true legally (we wont really know until it is tested in court), but I think there's a huge difference in practice.
Siri Recap is an electronic record of a conversation that includes timestamps. Imagine for example that during a scheduled meeting with my boss, he threatens to fire me for not doing something illegal. I now have strong evidence that this was said (even if it cant be officially attributed to him) during the time I was in a meeting with him. Not saying this will hold up in court, but it certainly is more damning that having written notes (not to mention the fact that my boss probably wouldn't say this when I am taking written notes).
Making that feature illegal may backfire spectacularly across the whole IT sector. What Apple does is it inputs voice data into an AI program and that outputs some transformed output. If a court would rule that output in any way matches the input (to be classified as a "record") then the whole ethics principle of stealing other people's data and funneling it through AI to make it company's own, would be at risk.
I imagine no single spineless impotent modern court would risk a wrath of our new benevolent AI overlords calling them all criminals they really are.
