if I draw something on a piece of paper, scan it, and hash it, there's no way anyone (including me) can ever reproduce it!
It'll definitely be messed up, but not random, or at least not as much as in other ways. There's a significant percentage of the human factor, how does your hand move, which shapes will you think of, at which rate will you repeat the shame shapes etc.
It's not only about the drawing, it's about the scanning. Or take a picture: you'll get millions of pixels, and each of them will be slightly different. Even if you draw the same thing, or even if you scan the same piece of paper again, it will be different. Hashing it means a totally different result.