So you have these bankers boxes. It's evidence, sure. Now you gotta put someone on the stand to testify about the boxes, and why someone sufficiently high up at HSBC should have known what those boxes meant and ignored it. Beyond a reasonable doubt. You could get that conviction, but you might not. When you're using circumstantial evidence like that, you need a lot of different things that point to the same result. And they didn't have that. It wasn't a slam dunk.

Now, it's imaginable that if the same exact conduct happened with a small company run by an individual, they could've gotten the conviction. The reason is that when dealing with individuals, the alternative explanations are simply less plausible in creating reasonable doubt. It's easy for an HSBC executive to get on the stand and say: we just didn't know about those boxes--we have divisions in 100 countries and move trillions of dollars a year and it never popped up on the radar. With an individual where illegal transactions might be the bulk of the business, as was the case here, those alternative explanations are much less believable.