They do, and just like in your other example, they internalize it, they just don't realize they do it automatically because it "sounds good".
> Most grammatical understanding comes when (if!) you study a foreign language and then you find out that "find out" is a thing called a "phrasal verb".
That's super funny, isn't this taught in middle school or something? In Romania you study Romanian grammar from 5th to 8th grade (11/12 to 14/15), and you learn syntax, morphology, etc.
Does the average English speaker really not know about the term "phrasal verb"? :-)