Not necessarily, it's only traceable if you generate receipts on both sides. I don't know about EU law, but in the US, you only need to report cash deposits if they're over $10k, and if your deposits are always over $10k (e.g. you're a big retailer or something), another $10k here and there won't raise any eyebrows.
Cash is still king when it comes to corruption since it's easy to exchange it for favors w/o generating a receipt at all.