> they're going to get threatening emails from regulators saying "Hey, you don't have a cookie banner".

That literally does not happen. What world do you live in?

But just to entertain your scenario let's say that did happen: it still wouldn't matter because they could just reply and tell them why they don't need one...

They don't even have to reply, just make a note on your footer or something or have a page you can link to that explains it. I've done this before