Accounting is a highly regulated field. My local accountant is properly certified, and takes information security very seriously (in part because of well established precedent around liability and professional misconduct).
I don't mean this as a giant joke, but where do you find these accountants?
I'm not saying that they don't try to, but things that would be major security no-no's to people on HN are often a regular part of business for others (emailing photocopies of 'secure' documents, copy/pasting passwords, etc).