@semanticman
Oh boy. Haha. So I actually just watched someone irl kinda have a breakdown over the そうです family of expressions. They are quite complicated and frankly, I’ll give it my best shot but best case scenario someone from Bunpro finds this thread.
The first thing is context. For the grammar point you referred to that you believe should it should be correct to, has a very specific caveat:
This そう is utilized exclusively to make predictions/guesses about something based on visual information. It is relatively low confidence, so should not be used for things that are obvious.
You can’t make a correction into this new grammar point unless you are sure that the policeman is making a statement based on visual information and he’s doing so with low confidence. The issue with そうです and translating it into English is that when you use it, there’s the implication that you, the speak did some thinking/opinion forming on the statement that you’re about to make. It isn’t just parroting what you heard. This nuance is emphasized more in the grammar point:
Appearance: 様態 - Highlighting the way that things ‘appear’, or ‘seem’.
Furthermore, there’s also a vocab word for the expression そうです which highlights the use of the expression not as “I heard” but rather “it seems this way.” This is interesting because it’s sort of like Bunpro is trying to emphasize both usages by translating the grammar point consistently as “I heard” but providing a standalone vocab for “my impression is…”
So, there’s my attempt. And please, if someone sees mistake please correct me. Hopefully I didn’t misunderstand your question or mix things up! I have an inkling I made an error somewhere (all of these look so similar), but hopefully this provides some guidance.