Ever think about just how varied individual handwriting is... how many different ways there are to write an "a," as well as every other letter... or number for that matter???
To keep it simple think about just the numbers 0 - 9, and the different ways they may be written, and yet immediately recognized. In fact, we of course have automatic equipment in the Post Office dedicated to do just that: automatically read Zip Codes, in all sorts of handwriting!
Tim Chartier addressed mechanical digit-reading in a recent post here: