To that same argument, saying there is no evidence that it has reduced black market behavior is the exact same concept that would drive 'There's no evidence that it hasn't reduced bad actors".

AML isn't like the war on drugs because that's a silly pointless war, it's more like traffic laws. Are they still broken? All of the time.

Would you rather drive on roads without them?

It's that simple, AML makes the job harder to do which is known to be effective at making harder to do, or at least introduces fear of doing.