In the US, if you are withdrawing ~thousands of $ in cash, and they ask you what it is for, and your answer is "mattress" or "no answer" then you can be 100% ce

In the US, if you are withdrawing ~thousands of $ in cash, and they ask you what it is for, and your answer is "mattress" or "no answer" then you can be 100% certain they will file an SAR. However, there are probably so many SAR's that they would only be useful as a data point on an investigation triggered by something else, or if you get them frequently. Also, if over $10k they are automatically required to file a CTR on that, but I bet those are even less likely to trigger anything by themselves.