Taxing gains from cryptocurrencies is extreme to me too and I agree that it crosses the line. In that case, we can say that they're overstepping. The fact that they're in charge of the citizens of their country doesn't mean the citizens should have no power over themselves. They should have a right to privacy.
I agree to that, taxes should be with understanding between the two parties but in most cases I think it's not cause what the government do is make decisions that they can't carry on anytime soon leaving the masses in dilusion and be left with paying up taxes on specific basis, meanwhile the reasons why the taxes are allocated are not being exercised which is bad and with this I think it's theft on the higher notes cause what's to be done with the tax allocations are not done and in most cases taxes are not being notified to the users .
Ah! I'm surprised you agree that taxes should be agreed to by two parties, this is not a market bargain, if you allow people to dictate to the government, taxes paid will be unreasonable. If the rich people are doing all within their reach to evade the taxes, what do you think the commoners would do if they had the opportunity? People will always want all the money to be sincere and I do not think it can move any country forward especially if they do not have natural resources that the government can depend mostly on. The only bad side to this is for the government to collect taxes and not be accountable for it. Most governments are just corrupt and irresponsible, but this is a different ballgame from the context of the tax payment itself.