I don't know if it's really easy for states to regulate crypto. The more they regulate them, the more they legitimize them. Then they have a big problem with convincing people that their fiat (dollar, euro etc.) that they're printing like madmen are better than bitcoin ! If I'm going to declare all my BTC holdings, income, dealings, etc., then I will start asking for my salary to be paid in BTC too ! Things start like that and soon enough nobody wants the official currency, like is happening in countries like Zimbabwe or Venezuela.
States are better off dismissing crypto IMHO, calling it something for hobbyists and criminals.
These countries' extradition treaties with the US are ridiculous, that's the main reason. US taxes are not very high for a developped country so I can't really agree with people doing tax evasion there.
France will extradite murderers to the US, after a lengthy procedure, and a promise from the US and states that the death penalty will be off the table. For lesser crimes, very difficult. Case in point Roman Polanski.