I've not been reading further than the articles indicating the leak of bank's internal documents on this point, but I think the key is the following:
Banks use them to report suspicious behaviour but they are not proof of wrongdoing or crime.
'
Not proof of wrongdoing and crime'
So the documents revealed are only documents used to report suspicious behaviour. Whether the behaviour is illicit or not, is a different question. The documents in questions supposedly were only meant to inform authorities about potential money laundering, giving authorities essential insight on what is happening and where.
And even if the behaviour found is illicit, the question is whether the bank is supposed to find out or the government agencies tasked with preventing money laundering.
If the banks are supposed to do so in given circumstances, there is a thick grey line between
knowing without doubt that the account is used for illicit purposes and
suspecting that the account is used for illicit purposes. And of course government agencies will look at these cases in hindsight, knowing a lot more and having a lot more information channels and authority available to investigation than the banks at the moment the banks look into it.
In all fairness, I think banks are between a rock and a hard place when it comes to money laundering.
If they would simply block an account when they suspect illicit transactions, we would see many, many user complaints and law suits directed at banks by customers and consumer organisations. If, on the other hand, they are more relaxed about blocking accounts, the public moans if - in hindsight - money appeared to have been laundered via a bank account.
You can't have both so what do you choose?