I ran across this video a while ago on what can happen to you if you don't pay your taxes. At some point during your Bitcoin career, the cryptocoin will be converted to fiat and that's how they will catch you.
https://www.youtube.com/watch?v=hf2fNEUPjQwIf government want taxes from bitcoin, they can get it from bitcoin trade. In my opinion, its better bitcoin trade get taxes and government issueing regulation on bitcoin trade, thats make bitcoin investor more confident