I disagree. the government can tell (and has told) everyone that certain bitcoins are radioactive, making it hard or even impossible to spend them. There was a Matt Levine article about bitcoin laundering. It is much harder than I thought.
The problem is that, even if you think this is the kind of thing the government should be able to do, they haven't told me which ones are "radioactive". So if someone uses one of those bitcoins to buy something from me, I might have trouble spending it afterwards. Failures of fungibility like that are potentially a big problem for a currency. So far they're only a small problem for Bitcoin, but as these examples show, they have the potential to become significant. That might create pressure to move to a coin like ZCash, Monero, or Mimblewimble which has built-in safeguards against such things.
how much harder. If Canadians government make some bitcoin radioactive i’m sure bitcoin trader in china would not mind giving me ETH in exchange for some bitcoin.
