> In a "hands off" scenario where the only only factor for companies becomes "avoid losing a civil lawsuit for Failing To Do Enough to stop a criminal you assisted", they will still create an opaque system with no due-process/oversight/recourse. They will do that by default, because it's cheaper.

I can understand the theoretical argument that they would. But in reality they didn't prior to the (relatively) recent AML laws, and other entities not subject to those laws largely don't.