True, and unfortunately for them they have the burden of proof as to whether or not we actually own/have access to XYZ cryptos. The IRS can't just come to your door and say "you made money on a crypto network and we want our cut." They have to prove it first. Ultimately this whole revolution will force governments to establish a different tax model all-together, perhaps a toll/ fee and license based tax system similar to what many libertarians say is fairer. After all why should I be forced to pay for a bridge that I never use (even vicariously)?