I have the same basic prior as you in terms of disbelieving claims of an eidetic memory, however, I could certainly believe it about Von Neumann specifically. Even if it’s extremely rare, there’s a quite a few documented cases of extraordinary memories in history (Kim Peek, Shereshevsky, etc.). Now if we assess this as a claim that he had perfect recall of 600,000 words after having read it, probably do agree with you, but the actual mechanics of this claim i.e. repeating back word for word a book probably starts at the beginning and proceeds from there—hence, this reduces to knowing the first few pages of a book really well on a single reading. He apparently learned many languages at a young age, so that lends additional evidence towards him having a high verbal intelligence of which memory is a component.
I have the same basic prior as you in terms of disbelieving claims of an eidetic memory, however, I could certainly believe it about Von Neumann specifically. Even if it’s extremely rare, there’s a quite a few documented cases of extraordinary memories in history (Kim Peek, Shereshevsky, etc.). Now if we assess this as a claim that he had perfect recall of 600,000 words after having read it, probably do agree with you, but the actual mechanics of this claim i.e. repeating back word for word a book probably starts at the beginning and proceeds from there—hence, this reduces to knowing the first few pages of a book really well on a single reading. He apparently learned many languages at a young age, so that lends additional evidence towards him having a high verbal intelligence of which memory is a component.