[elcapitan]

Because in cursive writing, the letters are connected - that's something that works in high quality, high effort script fonts. They way they do it is to use OpenType replacement features for various combinations of letters. For example, there are a bunch of a's in one font, and when the OpenType system detects a+n, it chooses the a that is drawn to connect with the n. There also may be different versions of the letters, so that the text gets more rhythm (like naturally written).

It would actually be an interesting machine learning application not only to recognize letters from an actual sample (say a document in cursive writing), but also to understand how the letters connect and then create a cursive font based on that.