I think it is not realistic to be deaf in the country for every citizen, how much he owns crypto-currencies. Yes, and still recover the tax from it. To be able to collect taxes, the state should control the system itself, where the crypto currency is actually used - and this is not realistic for a single country. Scales are too huge.
Well, for me, I see taxing as a way of protecting its users against negative entities that might eye to take advantage of its users. I think that as more and more people get their attention shift and set into cryptocurrency that gives more reasons for the assets of its users to be protected. If a government imposes laws and taxes on it, it gives and implied promise that the government would also protect and safeguard the rights of its users. So that, if something untoward will happen, the person won't just have to weep and swallow it without hope of getting something back, or at least, punishing those who did the offense to him. So, in general, I think it would be for the best.
I don't agree with what you said, no one can protect us from the thefts or any other mishaps in the crypto world as the government doesn't guarantee to keep your crypto funds safe and all other crap, they just want to milk you and get some money while you keep on suffering so they take taxes from you even if you are holding some crypto even through there isn't any way possible to know who holds what amount, they still let you believe that they are watching everything and people pay the taxes in fear if they are applied.