I'm honestly surprised we don't see this more often. Back in the old days (you know, when cards were actually signed as opposed to stickers)...companies would often send representatives to witness the signing. With the modern "hits" craze where everything needs to be signed...that simply isn't possible anymore.
Of course, even in the "old days" things still happened. I know some of the Pro Line Portraits cards were autopenned (probably for the same reason...so many players were signing cards the company couldn't witness them all). Another example is Donnie Shell in the 1997 UD Legend football set. Apparently his wife signed a significant number of the cards...so there are 2 varieties, the "authentic" card and the "wife" card. lol.