As someone who's spent countless hours combing through Ancestry.com's databases of "transcribed" public records while researching my own family history, I can say with some certainty that it's not just OCR that struggles with handwriting.

I'd say that at least a third, and probably more like half, of the records I've found on Ancestry.com which reference the folks I'm researching, are transcribed incorrectly.

Certainly part of the problem is that the people doing the transcribing aren't familiar with the names they're transcribing (I've had a DuBois written as both "Delrie" and "Dobins"). Another part of the problem is that when you're looking at handwritten records from well over a hundred years ago, often they're just plain hard to read (or even illegible).

Anyway, that second point, IMO, makes using Ancestry's efforts as an example of issues with "handwriting" in general a bit dodgy. The problems they face are more along the lines of dealing with old, faded, often poorly filmed documents where even a human will have a tough time.