Even the stuff that doesn't change, like the word "BIRTH"? And if so, why would they do that? Why not change just the personal data?
I can answer your question.
The answer is simple, the length of the names can change the space used and with it the location of the information.
For instance "Joe Doe" takes up less space than say "Aleksandr Isayevich Solzhenitsyn" so depending on the name originally on such a document it may not have been possible to match the spacing used by the original text. Remember that the photoshop program cannot match whatever program the State of Hawaii used to generate their documents, so to get the proper spacing the easiest way to do so and make it look official is to use a blank sheet.
I was asking why change the headers, which are static information? What you are saying doesn't answer that.