Oh, there are countless ways governments can regulate crypto currencies without such regulation being built into the currencies themselves. Right now, crypto currencies are entirely useless for 99 percent of real world purchases. You cannot buy a cup of coffee with your satoshis. All you can do is to buy a few digital assets and a tiny fraction of the world's real assets. You might as well try to buy dinner with your facebook stock or to pay your rent with cacao or tulips.
Let's say that government decides the only legal tender for purchasing real estate is the government's fiat currency of choice, for example euros or dollars, and that the only way to obtain a deed or to legally borrow money is to show through a government run website that you paid for the real estate with that fiat currency. That's it. Now government indirectly controls crypto currencies. You can develop all the crypto currencies you want, but if you can't use it for purchasing real estate, the ramifications of that constraint will trickle down through almost anything else. Then receiving rent in crypto is less interesting. then being paid in crypto is useless.
And about that: Want to pay or receive a salary? What if government says that can only happen with fiat and that any attempt of paying or receiving salary in crypto currencies is a felony that will land you in a fiat funded correctional facility for years? You would think twice. How will government know? The same way they know that you bought drugs: Through witnesses, agents, ISPs telling on you etc. It doesn't have to be 100 percent efficient. If they have the ability to catch 0.01 percent of transactions and the punishment is severe, most people will not do it. Don't tell me that crypto is encrypted and anonymous. As soon as you use it for a real world thing, you leave traces. You buy a car; someone sold it. Someone heard. Someone saw. You can't show a fiat transaction; that will be the proof that legislator says is enough to convict you. If government decides to make crypto illegal, or to make certain transactions illegal when paid with crypto, crypto will only be good for the grey economy.
Or what if government said that no matter in what currency you make your money, taxes have to be settled in fiat.
The point is that all government has to do is to ensure that fiat is needed for certain key parts of the economic system. Then people will need fiat, and government can then focus on regulating the exchanges between fiat and crypto. There is a very limited number of banks, and a small number of payment providers and a small number of ISPs. They just need to ensure that these organisations enforce the rules (register who bought or sold what crypto currency etc.). Pretty soon, the only crypto currency that 99 percent would use would be the government backed one, the one that had backdoors or whatever government demanded built in.