I am confused.
I see

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...hashing functions don’t generate uniformly distributed numbers
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Isn't this exactly what I am proving? That the functions / results DO form uniformly, over x sized range, within y amount of keys?
By you saying, "...actually proving that cryptographic and hashing functions don’t generate uniformly distributed numbers", that means you believe the hashes do generate uniformly numbers, correct? If so, what is so hard to understand lol?!
Absolutely not. "Uniform" means that each hash has the same probability of appearing — in other words, all hashes are equally likely. You're confusing this concept with the idea that hashes are, on average, evenly spaced, but that’s false — it’s a common fallacy.
If hashes are uniformly distributed, then by definition, there's no way to know where they are with more or less probability, since each one has exactly the same probability of appearing.
If you find a way to determine where a hash is more or less likely to appear, then the distribution is no longer uniform.