I disagree. The ink from the ribbon will also show grey depending on how much the ribbon has been saturated with ink. I've taken photos of older documents (family genealogy) and the type comes out grey... something to do with indoor lighting and having to get close. Also, I still have some of those old carbon papers and they come in dark blue and black and tend to leave smudges on the "copy" page. I've never thought this one was a "carbon copy" and still don't.
This was done with a typewriter, no doubt. Look at the capital As in “OBAMA.” In every case, they’re darker, an indication of a misalignment so that particular key strikes harder than others.