> to write is different from to rewrite

Only if you use dictionary meanings of words. Otherwise it really is not different. 99.99% of all meaningful code is not gotten right on the first try. As said above, you have to iterate on it.

> I'm referring to the fact that code can be made into libraries, or APIs if you're so keen on collecting rent

Name one library -- that is NOT just a network client for a paid SaaS service -- and then maybe I'll understand what point you're trying to make. And even if you find one, they are a vanishingly small, undetectable, minority.