Think of bitcoin as the bank account, and zerocoin as ATM withdrawals of cash. It's a leaky metaphor, but it fits. Since withdrawing money from an ATM is not

Think of bitcoin as the bank account, and zerocoin as ATM withdrawals of cash. It's a leaky metaphor, but it fits. Since withdrawing money from an ATM is not money laundering, it works. What makes it anonymous is that anyone can now start a 'bitcoin account' with purely unconnected zerocoins without any AML paperwork to go through just like a real life equivalent of dumping stacks of cash at your no questions asked numbered bank account service.