What do you mean? Aren't they inherently tamperproof?

> how would they find those dealing everything in bitcoin?

A few people might live that way, but unless the entire supply chain is bitcoin someone will have to buy the food/gas/land they need with govcoin and sell it in bitcoin, thus getting caught.

> One of the reason of URSS going down was the huge administrative costs of spying / investigating, keeping up the oppression on its citizens.

Since ever single transaction is tracked, you can automate 90% of the work. Just look for businesses making the same amount of purchases but less sales, or people sending money to or getting money from accounts that aren't registered as employers or stores. With modern anomaly detection techniques you'd hardly have to torture anyone.

The USSR just didn't have modern technology. It would have taken a team of agents to tail a single person; the ARGUS-IS can track everyone in a 36 square mile area with a single drone.