It would be astonishing if the money from each aircraft were not counted and documented before being bagged; the sales receipts would have to reflect to difference in stocks on board, which could and probably would be audited. Otherwise cabin staff, and/or base staff, would be wide open to accusations of theft, either of goods or of cash, or both. It's basic accounting, and whatever one might think of Ryanair, I don't believe a word of the "undocumented" story..