- A bank executive opens an account to a seemingly legit company.
- The compliance department OKs the account opening.
- A bank teller receives 50k USD in cash every month.
- Another teller receives another 50k USD in cash every month.
- The head of the branch doesn't report strange activity.
- The AML system by the bank don't detect anything strange.
...
Every one of those steps, and many more, are needed for this kind of operation. Who do you send to prison? Do you make the CEO responsible even though she probably had no idea that this was going on? Or do you send the bank teller to prison, who was just doing her job, and maybe even threatened by the cartels?
Even if the branch manager was getting paid by the cartels in order to not file AML reports, the payments were definitely happening in cash, so the conviction would have to be made based on eye-witnesses rather than an actual paper trail (good luck with that).
Another important thing is that if you look at the report, they blame HSBC for failing to properly monitor the transactions, framing the institution more as a victim than an accomplice of the cartels. So in reality, it's the cartels doing the money laundering, the bank is just a gear in the whole system.