That's the big question, isn't it? I suspect they just don't care. I'm sure the "props" they're selling are just line items in a spreadsheet, and they don't think they have to do the work to authenticate them. It's easier to just catalog and sell, and not worry about it until the item gets called out enough. Even if a only a few "fakes" slip through and sell, they certainly made their money back, and can afford to deal with the returns.The amount of fakes let us know that these are not mistakes. These aren’t sellers who bought these in other auctions and truly believed what they bought to be real, and are now selling off their collection.
These appear to be consigners who are Legitimately going out of their way to forge letters of authenticity, all in an attempt to fraud the public. In any other situation, like selling art in a gallery, this would be a crime and be investigated. The only question is: is Hetitage Auctions aware that it is happening, and complicit by ignoring the facts and looking the other way?
I'm sure the fakers know this, as well.