I think you have to ask why anyone would write a program to do this either.
Since this Bamie BC II was released my wife sent me a couple of documents that she scanned at her office and they came to me as pdfs. I asked her how she converted them to pdfs and she had no clue. It was just what the scanner sent to her computer. And all the pixels on the documents she sent were of uniform size.
ML/NJ
No one would write a program with the intent of doing this either. Machine-driven processes are inherently imperfect. If a program is attempting to differentiate text from non-text, for example, there may be stray pieces of text that the program is unable to recognize as text.