Depends on the document, the entity digitizing it, and the purpose for which it's being digitized.
Extraction-of-content only is often done on very inexpensive capture stations (Google OEMs one for their own book-scanning needs).
Archiving documents for remote viewing/research/posterity is often done at standards as high or higher than commercial art reproduction.
As one (extreme) point of reference, the US Constitution is a "government document". As are immigration/birth/death records where small hand written notes and minor typographic differences (e.g. how someone's name was spelled when the immigrated: is that an "o" or an "a") are very important. As are, in some countries, diaries/notes/meeting-agendas of politicians where a researcher may want a high quality of reproduction to, for instance, analyze the handwriting to get an idea of the physical state of the author or to authenticate who wrote it. As are a dozen other categories of paper based documents. It's easy to forget in a world of searchable email and video recordings of every major event that for the majority of the history of even a country as young as the US that the only records of many historical events are found in hand written or type-writer made notes; much of this history is in precarious position (degrading/fading/poorly-organized). Even in art history the ability to trace where/how certain artistic movements started and spread involves research into the hand written notes of whose work was displayed in what galleries, sold to whom etc. We do a lot of business in the
cultural heritage market. These institutions are very passionate about what they do and a huge part of the market uses digital backs.
But this is all off topic...
