This reminder just goes to show they are not really able to trace people who are into Bitcoin. If they are, they could have issued tax assessments even before these people are made liable for taxes under the law. The US government, as in this case, have to admit that their laws at present are no longer at par with times. And no matter how powerful their country is, there is no way they can exactly determine for themselves the people who are doing business with cryptocurrencies. Seems to me they only want to earn money from it without even categorically classifying the nature of the business of cryptos to begin with.
they are not YET ready to trace people,but they are trying their best:
https://www.chainalysis.com/it is not only bitcoin,they are trying it with zcash and monero-the most anonymous currencies
https://themerkle.com/governments-show-interest-in-firms-analyzing-monero-and-zcash-transactions/I am sure it is just a matter of time untill they are able to connect the dots and force you to pay taxes