okay but what about "c" being nearly the same as "z", neither of which look like the character and are nearly(?) identical. Is our brain supposed to just be able to figure it out?
O and 0 are very similar in lots of typefaces. And I and l and 1. Even u and v. Your brain's pretty good at figuring it out. Context helps a lot.
With narrow spacing and poor kerning it can get much worse, especially if you're reading printed text; I've seen some extremely bad fonts used in print, (usually in italics or titles, but sometimes in the body text as well):
m and rn, cl and d, lo and b, jo and p, ijl1, GC0OQ, italic Q2.