Typically (based on what I've been told by ex-IRS employees many years ago) when they receive a return in the mail, if it's hand written it's typically keyed in. If it's typed (as your turbotax return is) then it's just scanned in via an OCR reader.
Now this is based on what I was told over 10 years ago. Don't see any reason why it would not have been true then, or why it would not be true today.
