Similarly, is it also a crime for a buyer to purchase Bitcoins or other cryptocurrencies in a similar fashion without providing any ID? Isn't it also possible for the authorities to track via the seller's bank accounts the buyer's transaction details and trace back to the buyer, considering that a Bank to Bank transfer has taken place?
I think it depends on the amount. $20,000 a month or less isn't considered important. But that kid sold $50,000 without asking for ID. He was SELLING bitcoins for cash - in a hypothetical situation a drug dealer would try to turn his cash into bitcoin by purchasing from him.
With stuff like this, stick to the law people. And don't deal with huge amounts, it just triggers flags.