Fax is a secure channel, apparently, which of course is complete horseshit. It uses the phone network, which is only marginally better than the internet. Many know that email headers can be faked, but not so many know that phone numbers can, too.
Legally I guess this becomes the problem of the party that introduces the intermediate stages. The other party doesn't need to care.
Fax to TIFF to OCR to PDF to internet transfer to TIFF to fax
But anyone still requiring fax would probably just be happy "it came out of a fax machine / software."