Why do free pens handed out by companies almost always contain black ink instead of blue?

Black ink is preferred for duplication http://EzineArticles.com/5075723, since many scanners/photocopiers include a blue filter (which allows for "blue pencil" editing https://en.wikipedia.org/wiki/Blue_pencil_(editing) , but the websites of the promotional pen vendors I visited (e.g. http://www.bizpen.com/, http://www.pensrus.com/) generally offer a choice of blue or black ink for the same price. This means the buyer is choosing black more often than blue ink (in your observation, which I can share), for the above reason, or for any other reason they may have. Some of the cheapest pens may only come in black ink- e.g https://www.amazon.com/Cheap-Pens/s?k=Cheap+Pens

http://wiki.answers.com/Q/Should_legal_documents_be_signed_with_blue_or_black_pen#page2
I found this that kind of relates aswell. Basically, black used to be chosen as it used to show up better in the old ways if copying.... This doesn't exactly answer like above but.shows a slightly different approach xxx