I wouldn't call that a money laundering operation, but rather an unlicensed money transmitter. The latter is fairly common and carries much smaller penalties and less stigma.
Hmm. Not sure. A mixer only has one job - disguise the source of your funds.
That's not money laundering, which is
intentionally disguising the source of
illegally obtained funds. Moving around money without doing AML checks is a far cry from money laundering.
Now of course for most people it's for privacy, not disguising the proceeds of crime. I'm not sure the law can be bothered to delineate the difference. It's the intent of the service provider rather than the needs of the users that they'll go after.
That's the point -- they need to prove intent. That was easy with Helix because the operator apparently openly advertised it as a money laundering service and directly partnered with AlphaBay for that purpose. That showed intent.