In some cases it is. Wachovia (acquired by Wells Fargo) laundered drug money: https://www.theguardian.com/world/2011/apr/03/us-bank-mexico...

> Primarily, these involved deposits of traveller's cheques in euros. They had sequential numbers and deposited larger amounts of money than any innocent travelling person would need, with inadequate or no KYC [know your client] information on them and what seemed to a trained eye to be dubious signatures. "It was basic work," he says. "They didn't answer the obvious questions: 'Is the transaction real, or does it look synthetic? Does the traveller's cheque meet the protocols? Is it all there, and if not, why not?'"

I don't see how it's insane. In fact, it seems perfectly logical to me that you can't knowingly help people commit crimes.