Well, Isn't part of this not just the gray area of knowledge, that you don't know if a given pattern of activity is necessarily illegal, but the gray area of l

Well, Isn't part of this not just the gray area of knowledge, that you don't know if a given pattern of activity is necessarily illegal, but the gray area of law and even more, the gray area of legal and regulatory decisions, that the banker might not know if a given sort of activity would be considered worth prosecuting by given authorities according to their interests and priorities. And that bankers might indeed know that some flagrantly illegal activity might well be entirely ignored by authorities based on said authorities interests and the actors connections.