(1) Confirming prior response that if you print to the Adobe PDF PostScript printer driver instance, in fact it will fail. This is a feature built into Acrobat Distiller to prevent gratuitous removal of security on a PDF file.
(2) There are very good reasons for securing financial documents. Simply stated, an unsecured receipt or financial document can be too easily modified for criminal purposes. For example, a non-profit I was working with was scammed out of quite a bit of funds by a staff member who modified the incoming credit card invoices in PDF format to mask embezzling of funds. This protection has its inconveniences, but at least you don't need to worry about the integrity of the contents.
- Dov