Traditional currency isn't really anonymous. Sure it is theoretically possible to do an anonymous 150 million dollar cash transaction in USD but in practical terms it's basically impossible without a great deal of money laundering. I believe by law in North America banks have to report any cash transactions >= 10k per 24 hour period to the government. Additionally every bill has a traceable serial number on it.
There is no history of every transaction in which a given serial number appears however. So in that sense it's easier to hide origins... even if the Fed knows which bank got that note originally, it's very likely that there's no trace of it after that unless it was involved in a specific tracked transaction (uncover police drug buy, etc.)
In India, if you deposit more than Rupees 50,000 ( roughly USD 850) to another person's account in cash, you need to provide your PAN card number - which is a unique number issued by the Income Tax Authority. I am sure a huge number of transactions are done illegally beyond this system but the threshold for anonymous legal transactions is pretty low.
