A public ledger provides greater protection against 
  money laundering and other criminal activities than a 
  paper currency does

This is not true, especially when it comes to larger amounts.

For example, laundering millions of dollars in cryptocurrencies was easily achieved though services such as ShapeShift which up until recently had no KYC/AML paper trail. If someone wants to launder millions of dollars in physical cash, they would need a business acting as a "front" which could be scrutinized to an audit.

  The Bitcoin network allows anyone to move millions of 
  dollars across the world without any in-person 
  meetings, and without the approval of any financial institutions. 

https://www.nytimes.com/2018/07/13/technology/bitcoin-russia...

  The Russians also created Bitcoins themselves through 
  the process known as mining, the indictment said. 

This detail is particularly interesting, because if we assume state sponsored spies with a technical understanding of how the internet and the Bitcoin protocol works, that this sort of transaction could be untraceable to the source and so it would be safe to assume their operation was discovered though other forensics outside of blockchain records.